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Author name code: wang-jingxiu
ADS astronomy entries on 2022-09-14
=author:"Wang, Jing-Xiu" OR =author:"Wang, J.-X." OR =author:"Wang, J.X."
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Title: Characterization of Kepler targets based on medium-resolution
LAMOST spectra analyzed with ROTFIT
Authors: Frasca, A.; Molenda-Żakowicz, J.; Alonso-Santiago, J.;
Catanzaro, G.; De Cat, P.; Fu, J. N.; Zong, W.; Wang, J. X.; Cang,
T.; Wang, J. T.
2022A&A...664A..78F Altcode: 2022arXiv220504757F
<BR /> Aims: In this work we present the results of our analysis of 16
300 medium-resolution LAMOST spectra of late-type stars in the Kepler
field with the aim of determining the stellar parameters, activity
level, lithium atmospheric content, and binarity. <BR /> Methods: We
have used a version of the code ROTFIT specifically developed for the
LAMOST medium-resolution spectra to determine stellar parameters via
the adoption of a grid of spectra of real stars. We provide a catalog
with the atmospheric parameters (T<SUB>eff</SUB>, log g, and [Fe/H]),
radial velocity (RV), and projected rotation velocity (v sin i). For
cool stars (T<SUB>eff</SUB> ≤ 6500 K), we also calculated the Ha
and Li Iλ6708 equivalent width, which are important indicators of
chromospheric activity and evolutionary stage, respectively. <BR />
Results: From the sample of 16 300 spectra, we have derived the RV and
atmospheric parameters for 14 300 spectra of 7443 stars. Literature
data (mainly from high- or medium-resolution spectra) were used for
a quality control of the results and to assess the accuracy of the
derived parameters. The T<SUB>eff</SUB> and log g values are in good
agreement with the literature, although their distribution displays
some clustering effects, which may be the result of the nonuniform
distribution of the templates in the parameter space. The most relevant
differences are found for [Fe/H], which appears to be overestimated
for metal-poor stars; this overestimation is also likely due to the
template grid. We propose a relation to correct the [Fe/H] values
derived with ROTFIT. We were able to identify interesting objects,
such as double-lined binaries, stars with variable RVs, lithium-rich
giants, and emission-line objects. Based on the Hα flux, we found
327 active stars. We were able to detect the Li Iλ6708 line and
measure its equivalent width for 1657 stars, both giants and stars
on the main sequence. Regarding the latter, we performed a discrete
age classification based on the atmospheric lithium abundance and the
upper envelopes of a few open clusters. Among the giants, we found 195
Li-rich stars, 161 of which are reported here for the first time. No
relationship is found between stellar rotation and lithium abundance,
which allows us to rule out merger scenarios as the predominant
explanation of the enrichment of Li in our sample. The fraction of
Li-rich giants, ≈ 4%, is higher than expected. <P />Full Tables C.2,
C.3, 2, 3, and 4 are only available at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/664/A78">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/664/A78</A>
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Title: The Nonuniformity of Poleward Flux Transport on the Solar
Surface: A Statistical Method Applied to Solar Cycles 21-24
Authors: Wang, Zi-Fan; Jiang, Jie; Wang, Jing-Xiu
2022ApJ...930...84W Altcode: 2022arXiv220316119W
The poleward migration of the active regions' magnetic flux on the solar
surface plays an important role in the development of the large-scale
field development, especially the polar-field reversal, which is a
key process in the Babcock-Leighton-type solar dynamos. The poleward
flux transport is nonuniform, centered around poleward surges as
suggested by previous observations. The strong, long-lasting surges are
related to activity complexes, and often result in violent polar-field
reversal. However, the nonuniformity of poleward flux transport has
not been evaluated quantitatively. We propose a statistical method
to analyze the poleward flux transport during solar cycles 21-24
by considering the frequency distributions of the magnetic field
at latitudes of poleward surges occurring during solar cycles. The
nonuniformity is quantified as the kurtosis statistics representing
the tailedness of the distributions. We test the method on results
of surface flux transport simulations, and apply it to WSO, National
Solar Observatory, MWO, and HMI data. We confirm that the poleward
surges are of significance during solar cycles 21-24 in general. The
kurtosis within a solar cycle is affected by different latitudes of the
magnetic field and different data sources. The southern hemisphere of
cycle 24 exhibits the largest kurtosis, agreeing with the super-surge
concept from previous work. The significant nonuniformity of poleward
flux transport originates from the nonrandomness of active regions,
which favors the activity complexes as the origin of poleward surges.
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Title: VizieR Online Data Catalog: Kepler targets class based on
LAMOST spectra (Frasca+, 2022)
Authors: Frasca, A.; Molenda-Zakowicz, J.; Alonso-Santiago, J.;
Catanzaro, G.; De Cat, P.; Fu, J. N.; Zong, W.; Wang, J. X.; Cang,
T.; Wang, J. T.
2022yCat..36640078F Altcode:
Spectral type, average atmospheric parameters (Teff, logg, and [Fe/H]),
radial velocity (RV) and projected rotational velocity (vsini) are
quoted in Table 2 for 7443 stars. <P />Table 3 reports the H-alpha
equivalent width and flux at the stellar surface for 327 targets. <P
/>Table 4 reports the LiI-6708 equivalent width and lithium abundance
for 1657 targets. <P />(5 data files).
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Title: Response of the Fe Kα line emission to the X-ray continuum
variability in the changing-look active galactic nucleus NGC 1566
Authors: Liang, W. C.; Shu, X. W.; Wang, J. X.; Tan, Y.; Zhang, W. J.;
Sun, L. M.; Jiang, N.; Dou, L. M.
2022JHEAp..33...20L Altcode: 2022arXiv220111050L
NGC 1566 is a changing look AGN known to exhibit recurrent X-ray
outbursts with each lasting for several years. The most recent X-ray
outburst is observed on 2018, with a substantial increase of 2-10 keV
flux by a factor of ∼24 than the historical minimum. We re-analyze
the XMM-Newton and NuSTAR observations covering the pre-outburst,
outburst and post-outburst epochs, and confirm the discovery of the
broad feature in the ∼5-7 keV band during the period of outburst
that could be interpreted as a relativistic Fe Kα emission line. Our
analysis suggests that its flux has increased in tandem with the 2-10
keV continuum, making it the second changing look AGN in which the broad
Fe Kα line responds to the X-ray continuum variability. This behavior
strongly supports the idea that X-rays originates in a corona above
the accretion disk, and disk reflection produces the relativistic Fe
Kα line. In addition, we find the response of narrow Fe Kα emission
line to the changes in the X-ray continuum on a time-scale as short
as four months, allowing to put the location of line-emitting region
at <0.1 pc, comparable to the size of optical BLR. By comparing to
the changing look AGN NGC 2992, the Fe Kα variation rate (the ratio
of Fe Kα variation to luminosity variation) in NGC 1566 appears
greater, which could be possibly explained by larger amount of gas
or Fe abundance responsible for producing the Fe Kα line for the
latter. The strength of variable broad Fe Kα line as well as the soft
X-ray excess emission appears to be correlated with the accretion rate,
which could be explained as due to the state transition associated
with the changing-look phenomenon.
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Title: A Dynamo-Based Prediction of Solar Cycle 25
Authors: Guo, Wei; Jiang, Jie; Wang, Jing-Xiu
2021SoPh..296..136G Altcode: 2021arXiv210801412G
The solar activity cycle varies in amplitude. The last Solar Cycle 24 is
the weakest in the past century. Sun's activity dominates Earth's space
environment. The frequency and intensity of Sun's activity follow the
solar cycle. Hence there are practical needs to know the amplitude of
the upcoming Solar Cycle 25. Dynamo-based solar cycle predictions not
only provide forecasts, but also offer an effective way to evaluate our
understanding of the solar cycle. In this article we apply the method
of the first successful dynamo-based prediction developed for Solar
Cycle 24 to predict Solar Cycle 25, so that we can verify whether the
previous success is repeatable. The prediction shows that Solar Cycle
25 would be about 10% stronger than Solar Cycle 24 with an amplitude
of 126 (international sunspot number Version 2.0). The result suggests
that Solar Cycle 25 will not be the beginning of a Maunder-like grand
solar minimum as suggested by some publications. The solar behavior in
about four to five years will confirm whether the prediction method
captures the key mechanism for solar cycle variability, which is the
polar field around the cycle minimum in our model.
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Title: Algebraic quantification of an active region contribution to
the solar cycle
Authors: Wang, Zi-Fan; Jiang, Jie; Wang, Jing-Xiu
2021A&A...650A..87W Altcode: 2021arXiv210404307W
Context. The solar dipole moment at cycle minimum is considered to be
the most reliable precursor with which to determine the amplitude of the
subsequent cycle. Numerical simulations of the surface flux transport
(SFT) model are widely used to effectively predict the dipole moment
at cycle minimum. An algebraic method was recently proposed to quickly
predict the contribution of an active region (AR) to the axial dipole
moment at cycle minimum instead of SFT simulations. The method assumes
a bipolar magnetic region (BMR) configuration of ARs, however most ARs
are asymmetric in configuration of opposite polarities, or have more
complex configurations. Such ARs evolve significantly differently from
those of BMR approximations. <BR /> Aims: We propose a generalized
algebraic method to describe the axial dipole contribution of an
AR with an arbitrary configuration, and evaluate its effectiveness
compared to the BMR-based method. <BR /> Methods: We employ mathematical
deductions to obtain the generalized method. We compare the results
of the generalized method with SFT simulations of observed ARs,
artificially created BMRs, and ARs with more complex configurations. We
also compare the results with those from the BMR-based method. <BR
/> Results: The generalized method is equivalent to the SFT model,
and precisely predicts the contributions of ARs to the dipole moment,
but has a much higher computational efficiency. Although the BMR-based
method has similar computational efficiency to the generalized method,
it is only accurate for symmetric bipolar ARs. The BMR-based method
systematically overestimates the dipole contributions of asymmetric
bipolar ARs, and randomly miscalculates the contributions of more
complex ARs. <BR /> Conclusions: The generalized method provides a
quick and precise quantification of the contribution of an AR to solar
cycle evolution, which paves the way for application in physics-based
solar cycle predictions.
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Title: Homologous Microflares with Mass Ejection and Plasma Heating
on the Quiet Sun
Authors: Jin, C. L.; Zhou, G. P.; Wang, J. X.
2021ApJ...914L..35J Altcode:
Study of microflares on the quiet Sun is extremely important in learning
the physics of both solar flare and atmospheric heating. Here, for the
first time, we report the detailed observations of two homologous
microflares from Atmospheric Imager Assembly (AIA) images and
Heliospheric Magnetic Imager magnetograms in a very quiet region. The
two microflares are observed clearly in the extreme ultraviolet and
faintly in the ultraviolet in AIA images. They have an area of 59
Mm<SUP>2</SUP> and 46 Mm<SUP>2</SUP>, and a duration of 25 minutes
and 22 minutes. The magnetic cancellation continuously takes place
during the microflares, and the magnetic flux decrease is apparent,
with a value of 4 10<SUP>18</SUP> Mx. The obvious mass ejections
are observed during the microflares, and dimming occurs during and
after the microflares. The velocity of mass ejection is up to 160 km
s<SUP>1</SUP>. For the two microflares, the time of peak intensity
in 30.4 nm precedes that of the coronal peak emission, up to 2.43.3
minutes. Their thermal energy is estimated to be 1.3 10<SUP>27</SUP>
erg and 2.5 10<SUP>26</SUP> erg, respectively, which heats the corona
up to 5.8 MK and 2.8 MK. There are many similarities of microflares
on the quiet Sun to major flares in the active regions.
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Title: Physical Parameters of the Eclipsing Binary System EPIC
202060577
Authors: Zhao, S. J.; Fu, J. N.; Wang, J. T.; Li, C. Q.; Wang, J. X.;
Zong, W. K.
2021AcASn..62...23Z Altcode:
EPIC 202060577 is an eclipsing binary system containing a B-type
primary star. From the K2 photometry, 45 secondary minimal times were
obtained. The orbital period is determined to be 1.019648 days and the
epoch formula is derived. Based on LAMOST (Large Sky Area Multi-Object
Fiber Spectroscopic Telescope) spectra, the ROTFIT program is used
to obtain spectral class, effective temperature, metal abundance
and surface gravity of the primary star, and calculate the radial
velocities. Through the PHOEBE (Physics Of Eclipsing Binaries)
modeling program and emcee (Affine Invariant Markov chain Monte
Carlo Ensemble Sampler) fitting program, a solution of the orbital
parameters is obtained and the influence of Rossiter-McLaughlin effect
on the radial velocity curve is analyzed. The final solution shows
that EPIC 202060577 is a detached eclipsing binary system with mass
ratio q=0.11, the spectral class of the primary star is B2/3. The
mass, radius and effective temperature of the primary and secondary
stars are M_1=12.56M_{⊙} and M_2= 1.39M_{⊙}, R_1=4.58R_{sun} and
R_2=1.85R_{rm sun}, T_1=18979 K and T_2=8710 K, respectively, here
M_{⊙} and R_{sun} are the solar mass and solar radius. According
to the physical parameters, the evolutionary phase of EPIC 202060577
is discussed.
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Title: Activity Complexes and a Prominent Poleward Surge during
Solar Cycle 24
Authors: Wang, Zi-Fan; Jiang, Jie; Zhang, Jie; Wang, Jing-Xiu
2020ApJ...904...62W Altcode: 2020arXiv200912483W
Long-lasting activity complexes (ACs), characterized as a series of
closely located, continuously emerging solar active regions (ARs), are
considered generating prominent poleward surges from observations. The
surges lead to significant variations of the polar field, which
are important for the modulation of solar cycles. We aim to study
a prominent poleward surge during solar cycle 24 on the southern
hemisphere, and analyze its originating ACs and the effect on the
polar field evolution. We automatically identify and characterize ARs
based on synoptic magnetograms from the Solar Dynamics Observatory. We
assimilate these ARs with realistic magnetic configuration into a
surface flux transport model, and simulate the creation and migration
of the surge. Our simulations well reproduce the characteristics
of the surge and show that the prominent surge is mainly caused by
the ARs belonging to two ACs during Carrington rotations 2145-2159
(2013 December-2015 January). The surge has a strong influence on the
polar field evolution of the southern hemisphere during the latter
half of cycle 24. Without the about one-year-long flux emergence in
the form of ACs, the polar field around the cycle minimum would have
remained at a low level and even reversed to the polarity at cycle 23
minimum. Our study also shows that the long-lived unipolar regions due
to the decay of the earlier emerging ARs cause an intrinsic difficulty
of automatically identifying and precisely quantifying later emerging
ARs in ACs.
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Title: VizieR Online Data Catalog: Sun active regions from 1976-2017
(Jiang+, 2019)
Authors: Jiang, J.; Song, Q.; Wang, J. -X.; Baranyi, T.
2020yCat..18710016J Altcode:
The Debrecen Photoheliographic Data (DPD) sunspot catalog (Baranyi+,
2016SoPh..291.3081B) is the most detailed and user-friendly catalog
at present. It provides the area and position data for each observable
sunspot and sunspot groups on a daily basis along with images of sunspot
groups, full-disk scans, and magnetograms starting from 1974 to the
present. <P />The Geostationnary Operational Environmental Satellites
(GOES) X-ray data are available from 1975 September onwards. We select
ARs that are larger than 800{micro}Hem from the beginning of 1976 to
the end of 2017. The 567 ARs that satisfy this requirement are singled
out as our samples. <P />(1 data file).
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Title: Accurate focusing technology for the coronal images
Authors: Zhang, X. F.; Liu, Y.; Li, X. B.; Song, T. F.; Zhao, M. Y.;
Wang, J. X.
2019SPIE11116E..1DZ Altcode:
Optical imaging has been widely used in many fields as a tool for
acquiring images, which can be used in microscopic observation,
medical analysis, remote sensing, and astronomical observation. In
the field of astronomical observations, it is very important to adjust
the focus of the coronagraph. Due to the significant differences of the
intensity between the corona and the solar photosphere, the ground-based
coronagraph usually adopt an occulter, which is a little larger than
the solar disk, to shield the light from the solar photosphere. In
absence of the Sun as reference, focusing of the coronagraph is much
harder than usual optical system. For the ground-based coronagraph,
we developed a method of focusing using the solar disk image behind
this disk occulter. Based on a series of images collected by shifting
the center of the solar disk, we extract edge information of the solar
disk and use the edge gradient algorithm to fit the focal length. This
method can reduce the error of manual focusing. We can precisely find
out the coronagraph focal point and obtain a clear coronal image,
which lays a foundation for the technical support about remote control
system of the coronagraph.
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Title: Magnetic flux participation in solar surface magnetism during
solar cycle 24
Authors: Jin, Chun-Lan; Wang, Jing-Xiu
2019RAA....19...69J Altcode:
This study aims at investigating surface magnetic flux participation
among different types of magnetic features during solar cycle
24. State-of-the-art observations from SDO/HMI and Hinode/SOT are
combined to form a unique database in the interval from April 2010
to October 2015. Unlike previous studies, the statistics presented in
this paper are feature-detection-based. More than 20 million magnetic
features with relatively large scale, such as sunspot/pore, enhanced
and quiet networks, are automatically detected and categorized from
HMI observations, and the internetwork features are identified from
SOT/SP observations. The total flux from these magnetic features reaches
5.9×10<SUP>22</SUP> Mx during solar minimum and 2.4×10<SUP>23</SUP>
Mx in solar maximum. Flux occupation from the sunspot/pore region is
29% in solar maximum. Enhanced and quiet networks contribute 18% and
21% flux during the solar minimum, and 50% and 9% flux in the solar
maximum respectively. The internetwork field contributes over 55%
of flux in the solar minimum, and its flux contribution exceeds that
of sunspot/pore features in the solar maximum. During the solar active
condition, the sunspot field increases its area but keeps constant flux
density of about 150G, while the enhanced network follows the sunspot
number variation showing increasing flux density and area, but the quiet
network displays decreasing area and somewhat increasing flux density
of about 6%. The origin of the quiet network is not known exactly,
but is suggestive of representing the interplay between mean-field
and local dynamos. The source, magnitude and possible importance of
‘hidden flux’ are discussed in some detail.
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Title: A magnetar-powered X-ray transient as the aftermath of a
binary neutron-star merger
Authors: Xue, Y. Q.; Zheng, X. C.; Li, Y.; Brandt, W. N.; Zhang,
B.; Luo, B.; Zhang, B. -B.; Bauer, F. E.; Sun, H.; Lehmer, B. D.;
Wu, X. -F.; Yang, G.; Kong, X.; Li, J. Y.; Sun, M. Y.; Wang, J. -X.;
Vito, F.
2019Natur.568..198X Altcode: 2019arXiv190405368X
Mergers of neutron stars are known to be associated with short
γ-ray bursts<SUP>1-4</SUP>. If the neutron-star equation of state is
sufficiently stiff (that is, the pressure increases sharply as the
density increases), at least some such mergers will leave behind a
supramassive or even a stable neutron star that spins rapidly with
a strong magnetic field<SUP>5-8</SUP> (that is, a magnetar). Such
a magnetar signature may have been observed in the form of the
X-ray plateau that follows up to half of observed short γ-ray
bursts<SUP>9,10</SUP>. However, it has been expected that some X-ray
transients powered by binary neutron-star mergers may not be associated
with a short γ-ray burst<SUP>11,12</SUP>. A fast X-ray transient (CDF-S
XT1) was recently found to be associated with a faint host galaxy, the
redshift of which is unknown<SUP>13</SUP>. Its X-ray and host-galaxy
properties allow several possible explanations including a short γ-ray
burst seen off-axis, a low-luminosity γ-ray burst at high redshift, or
a tidal disruption event involving an intermediate-mass black hole and
a white dwarf<SUP>13</SUP>. Here we report a second X-ray transient,
CDF-S XT2, that is associated with a galaxy at redshift z = 0.738
(ref. <SUP>14</SUP>). The measured light curve is fully consistent
with the X-ray transient being powered by a millisecond magnetar. More
intriguingly, CDF-S XT2 lies in the outskirts of its star-forming host
galaxy with a moderate offset from the galaxy centre, as short γ-ray
bursts often do<SUP>15,16</SUP>. The estimated event-rate density
of similar X-ray transients, when corrected to the local value, is
consistent with the event-rate density of binary neutron-star mergers
that is robustly inferred from the detection of the gravitational-wave
event GW170817.
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Title: Multiple Magnetic Reconnections Driven by a Large-scale
Magnetic Flux Rope
Authors: Zhou, G. P.; Tan, C. M.; Su, Y. N.; Shen, C. L.; Tan, B. L.;
Jin, C. L.; Wang, J. X.
2019ApJ...873...23Z Altcode:
Magnetic flux ropes (MFRs), as the most probable core structure
of solar eruptive activity, remain mysterious on their origination,
magnetic environment, and erupting mechanisms. Here, we newly identify
a large-scale hot channel MFR, named “MFR3”, that connects an
anti-Hale active region (AR) 11429 and a normal AR 11430 on 2012
March 7 based on multi-wavelength observations. An oscillation is
first detected at the top of MFR3 during 00:10-00:30 UT as triggered
by an X5.4 flare-related eruption of an MFR (named “MFR1” here)
in AR 11429. Then, after a quiet period of ∼20 minutes at around
00:52 UT, external magnetic reconnection (EMR) occurred above MFR3
manifested by not only bidirectional outflow in extreme ultraviolet
images, but also microwave quasi-periodic pulsation in broadband radio
spectral observations for the first time. With the occurrence of EMR,
the large-scale MFR3 quickly erupted at 01:01 UT and triggered an
X1.3 flare, which is related to the eruption of the other MFR (named
“MFR2” here) in AR 11429 at 01:05 UT. The erupting MFR3 and MFR2
appeared successively in the same associated halo coronal mass ejection
(CME) as two different core structures. The identification of the
large-scale MFR3 between two separated ARs and its complex activity
may shed new light on our understanding of the initiation mechanism
of a CME. Further work should lay emphasis on how a large-scale MFR3
forms in the solar atmosphere.
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Title: Different Contributions to Space Weather and Space Climate
from Different Big Solar Active Regions
Authors: Jiang, Jie; Song, Qiao; Wang, Jing-Xiu; Baranyi, Tünde
2019ApJ...871...16J Altcode: 2019arXiv190100116J
The purpose of this paper is to show that large active regions (ARs)
with different magnetic configurations have different contributions
to short-term and long-term variations of the Sun. As a case study,
the complex δ-type AR 12673 and the simple β-type AR 12674 are
investigated in detail. Since the axial dipole moment at cycle minimum
determines the amplitude of the subsequent cycle and space climate,
we have assimilated the individual observed magnetic configurations
of these two ARs into a surface flux transport model to compare their
contributions to the axial dipole moment D. We find that AR 12673 has
a significant effect on D at the end of the cycle, making it weaker
because of abnormal and complicated magnetic polarities. An initial
strongly positive D ends up with a strongly negative value. The
flare-poor AR 12674 has a greater contribution to the long-term
axial dipole moment than the flare-rich AR 12673. We then carry out a
statistical analysis of ARs larger than 800 μHem from 1976 to 2017. We
use the flare index FI and define an axial dipole moment index DI to
quantify the effects of each AR on space weather and space climate,
respectively. Whereas the FI has a strong dependence on the magnetic
configuration, the DI shows no such dependence. The DI is mainly
determined by the latitudinal location and the latitudinal separation
of the positive and negative magnetic fluxes of the ARs. Simple ARs
have the same possibility as complex ARs to produce big DI values
affecting space climate.
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Title: Variability-selected Low-luminosity Active Galactic Nuclei
Candidates in the 7 Ms Chandra Deep Field-South
Authors: Ding, N.; Luo, B.; Brandt, W. N.; Paolillo, M.; Yang, G.;
Lehmer, B. D.; Shemmer, O.; Schneider, D. P.; Tozzi, P.; Xue, Y. Q.;
Zheng, X. C.; Gu, Q. S.; Koekemoer, A. M.; Vignali, C.; Vito, F.;
Wang, J. X.
2018ApJ...868...88D Altcode: 2018arXiv181009465D
In deep X-ray surveys, active galactic nuclei (AGNs) with a broad range
of luminosities have been identified. However, cosmologically distant
low-luminosity AGN (LLAGN, {L}<SUB>{{X</SUB>}}≲ {10}<SUP>42</SUP>
erg s<SUP>-1</SUP>) identification still poses a challenge because
of significant contamination from host galaxies. Based on the 7 Ms
Chandra Deep Field-South (CDF-S) survey, the longest-timescale (∼17
years) deep X-ray survey to date, we utilize an X-ray variability
selection technique to search for LLAGNs that remain unidentified
among the CDF-S X-ray sources. We find 13 variable sources from 110
unclassified CDF-S X-ray sources. Except for one source that could
be an ultraluminous X-ray source, the variability of the remaining 12
sources is most likely due to accreting supermassive black holes. These
12 AGN candidates have low intrinsic X-ray luminosities, with a
median value of 7 × 10<SUP>40</SUP> erg s<SUP>-1</SUP>. They are
generally not heavily obscured, with an average effective power-law
photon index of 1.8. The fraction of variable AGNs in the CDF-S is
independent of X-ray luminosity and is only restricted by the total
number of observed net counts, confirming previous findings that X-ray
variability is a near-ubiquitous property of AGNs over a wide range of
luminosities. There is an anticorrelation between X-ray luminosity and
variability amplitude for high-luminosity AGNs, but as the luminosity
drops to ≲10<SUP>42</SUP> erg s<SUP>-1</SUP>, the variability
amplitude no longer appears dependent on the luminosity. The entire
observed luminosity-variability trend can be roughly reproduced by
an empirical AGN variability model based on a broken power-law power
spectral density function.
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Title: A unique distant submillimeter galaxy with an X-ray-obscured
radio-luminous active galactic nucleus
Authors: Shu, X. W.; Xue, Y. Q.; Liu, D. Z.; Wang, T.; Han, Y. K.;
Chang, Y. Y.; Liu, T.; Huang, X. X.; Wang, J. X.; Zheng, X. Z.;
da Cunha, E.; Daddi, E.; Elbaz, D.
2018A&A...619A..76S Altcode: 2018arXiv180900318S
<BR /> Aims: We present a multiwavelength study of an atypical
submillimeter galaxy, GH500.30, in the GOODS-North field, with the aim
to understand its physical properties of stellar and dust emission, as
well as the central active galactic nucleus (AGN) activity. Although
it is shown that the source is likely an extremely dusty galaxy
at high redshift, its exact position of submillimeter emission is
unknown. <BR /> Methods: We use NOEMA observation at 1.2 mm with
subarcsecond resolution to resolve the dust emission, and precisely
localize the counterparts at other wavelengths, which allows us to
better constrain its stellar and dust spectral energy distribution
(SED) as well as redshift. We carry out the new near-infrared (NIR)
photometry of GH500.30 observed with HST, and perform panchromatic SED
modelling from ultraviolet (UV)/optical to submillimeter. We derive the
photometric redshift using both NIR and far-infrared (FIR) SED modeling,
and place constraints on the stellar and dust properties such as stellar
mass, age, dust attenuation, IR luminosity, and star-formation rate
(SFR). The AGN properties are inferred from the X-ray spectral analysis
and radio observations, and its contribution to the total IR luminosity
is estimated from the broadband SED fittings using MAGPHYS. <BR />
Results: With the new NOEMA interferometric imaging, we confirm that
the source is a unique dusty galaxy. It has no obvious counterpart
in the optical and even NIR images observed with HST at λ ≲ 1.4
μm. Photometric-redshift analyses from both stellar and dust SED
suggest it to likely be at z ≳ 4, though a lower redshift at z ≳ 3.1
cannot be fully ruled out (at 90% confidence interval). Explaining its
unusual optical-to-NIR properties requires an old stellar population
(∼0.67 Gyr), coexisting with a very dusty ongoing starburst
component. The latter is contributing to the FIR emission, with its
rest-frame UV and optical light being largely obscured along our
line of sight. If the observed fluxes at the rest-frame optical/NIR
wavelengths were mainly contributed by old stars, a total stellar mass
of ∼3.5 × 10<SUP>11</SUP> M<SUB>⊙</SUB> would be obtained. An
X-ray spectral analysis suggests that this galaxy harbors a heavily
obscured AGN with N<SUB>H</SUB> = 3.3<SUP>+2.0</SUP><SUB>-1.7</SUB>
× 10<SUP>23</SUP> cm<SUP>-2</SUP> and an intrinsic 2-10 keV luminosity
of L<SUB>x</SUB> ∼ 2.6 × 10<SUP>44</SUP> erg s<SUP>-1</SUP>, which
places this object among distant type 2 quasars. The radio emission of
the source is extremely bright, which is an order of magnitude higher
than the star-formation-powered emission, making it one of the most
distant radio-luminous dusty galaxies. <BR /> Conclusions: The combined
characteristics of the galaxy suggest that the source appears to have
been caught in a rare but critical transition stage in the evolution
of submillimeter galaxies, where we are witnessing the birth of a young
AGN and possibly the earliest stage of its jet formation and feedback.
---------------------------------------------------------
Title: Predictability of the Solar Cycle Over One Cycle
Authors: Jiang, Jie; Wang, Jing-Xiu; Jiao, Qi-Rong; Cao, Jin-Bin
2018ApJ...863..159J Altcode: 2018arXiv180701543J
The prediction of the strength of future solar cycles is of interest
because of its practical significance for space weather and as a test of
our theoretical understanding of the solar cycle. The Babcock-Leighton
mechanism allows predictions by assimilating the observed magnetic
field on the surface. Since the emergence of sunspot groups has
random properties, making it impossible to accurately predict the
solar cycle and strongly limiting the scope of cycle predictions,
we develop a scheme to investigate the predictability of the solar
cycle over one cycle. When a cycle has been ongoing for more than
three years, the sunspot group emergence can be predicted along with
its uncertainty during the rest time of the cycle. The method for
this prediction is to start by generating a set of random realizations
that obey the statistical relations of the sunspot emergence. We then
use a surface flux transport model to calculate the possible axial
dipole moment evolutions. The correlation between the axial dipole
moment at cycle minimum and the subsequent cycle strength and other
empirical properties of solar cycles are used to predict the possible
profiles of the subsequent cycle. We apply this scheme to predict the
large-scale field evolution from 2018 to the end of cycle 25, whose
maximum strength is expected to lie in the range from 93 to 155 with
a probability of 95%.
---------------------------------------------------------
Title: A Long Decay of X-Ray Flux and Spectral Evolution in the
Supersoft Active Galactic Nucleus GSN 069
Authors: Shu, X. W.; Wang, S. S.; Dou, L. M.; Jiang, N.; Wang, J. X.;
Wang, T. G.
2018ApJ...857L..16S Altcode: 2018arXiv180900319S
GSN 069 is an optically identified very low-mass active galactic
nuclei (AGN) that shows supersoft X-ray emission. The source is known
to exhibit a huge X-ray outburst, with flux increased by more than
a factor of ∼240 compared to the quiescence state. We report its
long-term evolution in the X-ray flux and spectral variations over a
timescale of ∼decade, using both new and archival X-ray observations
from the XMM-Newton and Swift. The new Swift observations detected
the source in its lowest level of X-ray activity since the outburst,
a factor of ∼4 lower in the 0.2-2 keV flux than that obtained with
the XMM-Newton observations nearly eight years ago. Combining with the
historical X-ray measurements, we find that the X-ray flux is decreasing
slowly. There seemed to be spectral softening associated with the
drop of X-ray flux. In addition, we find evidence for the presence of
a weak, variable, hard X-ray component, in addition to the dominant
thermal blackbody emission reported before. The long decay of X-ray
flux and spectral evolution, as well as the supersoft X-ray spectra,
suggest that the source could be a tidal disruption event (TDE), though
a highly variable AGN cannot be fully ruled out. Further continued
X-ray monitoring would be required to test the TDE interpretation,
by better determining the flux evolution in the decay phase.
---------------------------------------------------------
Title: Linking black hole growth with host galaxies: the
accretion-stellar mass relation and its cosmic evolution
Authors: Yang, G.; Brandt, W. N.; Vito, F.; Chen, C. -T. J.; Trump,
J. R.; Luo, B.; Sun, M. Y.; Xue, Y. Q.; Koekemoer, A. M.; Schneider,
D. P.; Vignali, C.; Wang, J. -X.
2018MNRAS.475.1887Y Altcode: 2017arXiv171009399Y
Previous studies suggest that the growth of supermassive black holes
(SMBHs) may be fundamentally related to host-galaxy stellar mass
(M<SUB>⋆</SUB>). To investigate this SMBH growth-M<SUB>⋆</SUB>
relation in detail, we calculate long-term SMBH accretion rate as a
function of M<SUB>⋆</SUB> and redshift [\overlineBHAR(M_{\star },
z)] over ranges of log (M<SUB>⋆</SUB>/M<SUB>⊙</SUB>) = 9.5-12
and z = 0.4-4. Our \overlineBHAR(M_{\star }, z) is constrained by
high-quality survey data (GOODS-South, GOODS-North and COSMOS), and
by the stellar mass function and the X-ray luminosity function. At a
given M<SUB>⋆</SUB>, \overlineBHAR is higher at high redshift. This
redshift dependence is stronger in more massive systems [for log
(M<SUB>⋆</SUB>/M<SUB>⊙</SUB>) ≈ 11.5, \overlineBHAR is three
decades higher at z = 4 than at z = 0.5], possibly due to AGN
feedback. Our results indicate that the ratio between \overlineBHAR
and average star formation rate (\overlineSFR) rises towards high
M<SUB>⋆</SUB> at a given redshift. This \overlineBHAR/\overlineSFR
dependence on M<SUB>⋆</SUB> does not support the scenario that
SMBH and galaxy growth are in lockstep. We calculate SMBH mass
history [M<SUB>BH</SUB>(z)] based on our \overlineBHAR(M_{\star },
z) and the M<SUB>⋆</SUB>(z) from the literature, and find that the
M<SUB>BH</SUB>-M<SUB>⋆</SUB> relation has weak redshift evolution
since z ≈ 2. The M<SUB>BH</SUB>/M<SUB>⋆</SUB> ratio is higher
towards massive galaxies: it rises from ≈1/5000 at log M<SUB>⋆</SUB>
≲ 10.5 to ≈1/500 at log M<SUB>⋆</SUB> ≳ 11.2. Our predicted
M<SUB>BH</SUB>/M<SUB>⋆</SUB> ratio at high M<SUB>⋆</SUB> is similar
to that observed in local giant ellipticals, suggesting that SMBH
growth from mergers is unlikely to dominate over growth from accretion.
---------------------------------------------------------
Title: Automatic Solar Seeing Observations at Mt. Wumingshan in
Western China
Authors: Song, T. F.; Wen, Y. M.; Liu, Y.; Elmhamdi, A.; Kordi,
A. S.; Zhao, M. Y.; Zhang, X. F.; Li, X. B.; Wang, J. X.; Fu, Y.;
Cheng, X. M.; Xu, F. Y.
2018SoPh..293...37S Altcode:
Mountain Wumingshan (Mt. WMS) is located in the southeastern foot
of the Tibet Plateau with an altitude of 4,800 m. It is one of the
candidate sites to place China's next-generation large-scale solar
telescope. A temporary observation platform has been built at Mt. WMS,
but there is still a great need of a stable solar-seeing monitoring for
long-term observations. Based on the preliminary studies on the Solar
Differential Image Motion Monitor (SDIMM) of the Yunnan Observatories,
we built an improved version of this early prototype, which is
called Wumingshan Mountain Automated Solar Differential Image Motion
Monitor (WMA-SDIMM). We develop the automatic system of the WMA-SDIMM,
investigate the reliability and precision of our measurements by error
analysis and comparison testing, and present the statistical results
from October 2016 to September 2017 at Mt. WMS. WMA-SDIMM works very
well at Mt. WMS and is quite suitable for long-period daytime seeing
observations.
---------------------------------------------------------
Title: A prediction of the solar cycle 25
Authors: Jiang, Jie; Wang, Jing-Xiu; Jiao, Qi-Rong
2018IAUS..340..327J Altcode:
Here we report our recent prediction of the solar cycle 25 based on a
newly developed scheme, which is used to investigate the predictability
of the solar cycle over one cycle. The scheme is a combination of the
empirical properties of solar cycles and a surface flux transport model
to get the possible axial dipole moment evolution at a few years before
cycle minimum, by which to get the subsequent cycle strength based on
the correlation between the axial dipole moment at cycle minimum and
the subsequent cycle strength. We apply this scheme to predict the
large-scale field evolution since 2018 onwards. The results show that
the northern polar field will keep on increasing, while the southern
polar field almost keeps flat by the end of cycle 24. This leads to
the cycle 25 strength of 125 +/- 32, which is about 10% stronger than
cycle 24 according to the mean value.
---------------------------------------------------------
Title: A Study of External Magnetic Reconnection that Triggers a
Solar Eruption
Authors: Zhou, G. P.; Zhang, J.; Wang, J. X.; Wheatland, M. S.
2017ApJ...851L...1Z Altcode:
External magnetic reconnection (EMR) is suggested to play an
essential role in triggering a solar eruption, but is rarely directly
observed. Here, we report on a filament eruption on 2014 October 3
that apparently involves the process of an early EMR. A total of 1.7 ×
10<SUP>20</SUP> Mx flux was first canceled along the filament-related
polarity inversion line over 12 hr, and then the filament axis started
to brighten in extreme ultraviolet (EUV). An impulsive EUV brightening
began 30 minutes later, and we attribute this to EMR, as it is located
at the center of a bidirectional outflow with a velocity of 60-75 km
s<SUP>-1</SUP> along large-scale magnetic loops from active regions
NOAA 12178 and 12179, respectively, and over the filament mentioned
above. Following the EMR, the filament was activated; then, partial
eruption occurred 6 minutes later in the west, in which the decay
index above the magnetic flux rope (MFR) reached the critical value of
1.5. The observations are interpreted in terms of underlying magnetic
flux cancelation leading to the buildup and eventual formation of the
MFR with a filament embedded in it, and the MFR is elevated later. The
activated MFR rises and pushes the overlying sheared field and forms a
current sheet causing the EMR. The EMR in turn weakens the constraining
effect of the overlying field, leading to the arising of the MFR,
and subsequently erupting due to torus instability.
---------------------------------------------------------
Title: Deepest View of AGN X-Ray Variability with the 7 Ms Chandra
Deep Field-South Survey
Authors: Zheng, X. C.; Xue, Y. Q.; Brandt, W. N.; Li, J. Y.; Paolillo,
M.; Yang, G.; Zhu, S. F.; Luo, B.; Sun, M. Y.; Hughes, T. M.; Bauer,
F. E.; Vito, F.; Wang, J. X.; Liu, T.; Vignali, C.; Shu, X. W.
2017ApJ...849..127Z Altcode: 2017arXiv171004358Z
We systematically analyze the X-ray variability of active galactic
nuclei (AGNs) in the 7 Ms Chandra Deep Field-South survey. On the
longest timescale (≈17 years), we find only a weak (if any)
dependence of X-ray variability amplitudes on energy bands or
obscuration. We use four different power spectral density (PSD)
models to fit the anticorrelation between normalized excess variance
({σ }<SUB>{nxv</SUB>}<SUP>2</SUP>) and luminosity, and obtain a
best-fit power-law index β ={1.16}<SUB>-0.05</SUB><SUP>+0.05</SUP>
for the low-frequency part of the AGN PSD. We also divide the whole
light curves into four epochs in order to inspect the dependence
of {σ }<SUB>{nxv</SUB>}<SUP>2</SUP> on these timescales, finding
an overall increasing trend. The analysis of these shorter
light curves also infers a β of ∼1.3 that is consistent
with the above-derived β, which is larger than the frequently
assumed value of β =1. We then investigate the evolution of {σ
}<SUB>{nxv</SUB>}<SUP>2</SUP>. No definitive conclusion is reached
because of limited source statistics, but if present, the observed
trend goes in the direction of decreasing AGN variability at fixed
luminosity toward high redshifts. We also search for transient events
and find six notable candidate events with our considered criteria. Two
of them may be a new type of fast transient events, one of which is
reported here for the first time. We therefore estimate a rate of fast
outbursts < \dot{N}> ={1.0}<SUB>-0.7</SUB><SUP>+1.1</SUP>×
{10}<SUP>-3</SUP> {{galaxy}}<SUP>-1</SUP> {{yr}}<SUP>-1</SUP> and a
tidal disruption event (TDE) rate < {\dot{N}}<SUB>{TDE</SUB>}>
={8.6}<SUB>-4.9</SUB><SUP>+8.5</SUP>× {10}<SUP>-5</SUP>
{{galaxy}}<SUP>-1</SUP> {{yr}}<SUP>-1</SUP> assuming the other four
long outbursts to be TDEs.
---------------------------------------------------------
Title: Tracing the accretion history of supermassive black holes
through X-ray variability: results from the ChandraDeep Field-South
Authors: Paolillo, M.; Papadakis, I.; Brandt, W. N.; Luo, B.; Xue,
Y. Q.; Tozzi, P.; Shemmer, O.; Allevato, V.; Bauer, F. E.; Comastri,
A.; Gilli, R.; Koekemoer, A. M.; Liu, T.; Vignali, C.; Vito, F.;
Yang, G.; Wang, J. X.; Zheng, X. C.
2017MNRAS.471.4398P Altcode: 2017arXiv170705332P
We study the X-ray variability properties of distant active galactic
nuclei (AGNs) in the ChandraDeep Field-South region over 17 yr, up
to z ∼ 4, and compare them with those predicted by models based
on local samples. We use the results of Monte Carlo simulations to
account for the biases introduced by the discontinuous sampling and
the low-count regime. We confirm that variability is a ubiquitous
property of AGNs, with no clear dependence on the density of the
environment. The variability properties of high-z AGNs, over different
temporal time-scales, are most consistent with a power spectral density
(PSD) described by a broken (or bending) power law, similar to nearby
AGNs. We confirm the presence of an anticorrelation between luminosity
and variability, resulting from the dependence of variability on black
hole (BH) mass and accretion rate. We explore different models, finding
that our acceptable solutions predict that BH mass influences the value
of the PSD break frequency, while the Eddington ratio λ<SUB>Edd</SUB>
affects the PSD break frequency and, possibly, the PSD amplitude as
well. We derive the evolution of the average λ<SUB>Edd</SUB> as a
function of redshift, finding results in agreement with measurements
based on different estimators. The large statistical uncertainties make
our results consistent with a constant Eddington ratio, although one of
our models suggest a possible increase of λ<SUB>Edd</SUB> with lookback
time up to z ∼ 2-3. We conclude that variability is a viable mean to
trace the accretion history of supermassive BHs, whose usefulness will
increase with future, wide-field/large effective area X-ray missions.
---------------------------------------------------------
Title: VizieR Online Data Catalog: 16yrs of AGNs X-ray spectral
analyses from 7Ms CDF-S (Liu+, 2017)
Authors: Liu, T.; Tozzi, P.; Wang, J. -X.; Brandt, W. N.; Vignali,
C.; Xue, Y.; Schneider, D. P.; Comastri, A.; Yang, G.; Bauer, F. E.;
Paolillo, M.; Luo, B.; Gilli, R.; Wang, Q. D.; Giavalisco, M.; Ji,
Z.; Alexander, D. M.; Mainieri, V.; Shemmer, O.; Koekemoer, A.;
Risaliti, G.
2017yCat..22320008L Altcode:
The 7Ms CDF-S survey is comprised of observations performed between
1999 October 14, and 2016 March 24, (UTC). Excluding one observation
compromised by telemetry saturation and other issues (ObsID 581),
there are 102 observations (observation IDs listed in Table 1) in
the data set. The exposures collected across 16 years can be grouped
into four distinct periods, each spanning 2-21 months. <P />Table 1:
---------------------------------------------------------------------------
Period Observation Date Time Span Exposure Time
---------------------------------------------------------------------------
I 1999.10-2000.12 14 months 1Ms 11 ObsIDs: 1431-0 1431-1 441 582 2406
2405 2312 1672 2409 2313 2239 <P />II 2007.09-2007.11 2 months 1Ms 12
ObsIDs: 8591 9593 9718 8593 8597 8595 8592 8596 9575 9578 8594 9596
<P />III 2010.03-2010.07 4 months 2Ms 31 ObsIDs: 12043 12123 12044
12128 12045 12129 12135 12046 12047 12137 12138 12055 12213 12048 12049
12050 12222 12219 12051 12218 12223 12052 12220 12053 12054 12230 12231
12227 12233 12232 12234 <P />IV 2014.06-2016.03 21 months 3Ms 48 ObsIDs:
16183 16180 16456 16641 16457 16644 16463 17417 17416 16454 16176 16175
16178 16177 16620 16462 17535 17542 16184 16182 16181 17546 16186 16187
16188 16450 16190 16189 17556 16179 17573 17633 17634 16453 16451 16461
16191 16460 16459 17552 16455 16458 17677 18709 18719 16452 18730 16185
---------------------------------------------------------------------------
<P />(4 data files).
---------------------------------------------------------
Title: Black Hole Growth Is Mainly Linked to Host-galaxy Stellar
Mass Rather Than Star Formation Rate
Authors: Yang, G.; Chen, C. -T. J.; Vito, F.; Brandt, W. N.; Alexander,
D. M.; Luo, B.; Sun, M. Y.; Xue, Y. Q.; Bauer, F. E.; Koekemoer,
A. M.; Lehmer, B. D.; Liu, T.; Schneider, D. P.; Shemmer, O.; Trump,
J. R.; Vignali, C.; Wang, J. -X.
2017ApJ...842...72Y Altcode: 2017arXiv170406658Y
We investigate the dependence of black hole accretion rate (BHAR) on
host-galaxy star formation rate (SFR) and stellar mass (M <SUB>*</SUB>)
in the CANDELS/GOODS-South field in the redshift range of 0.5≤slant
z< 2.0. Our sample consists of ≈ {{18,000}} galaxies, allowing us
to probe galaxies with 0.1{M}<SUB>⊙ </SUB>{{yr}}<SUP>-1</SUP>≲
{SFR}≲ 100 {M}<SUB>⊙ </SUB> {{yr}}<SUP>-1</SUP> and/or
{10}<SUP>8</SUP>{M}<SUB>⊙ </SUB>≲ {M}<SUB>* </SUB>≲
{10}<SUP>11</SUP> {M}<SUB>⊙ </SUB>. We use sample-mean BHAR to
approximate long-term average BHAR. Our sample-mean BHARs are derived
from the Chandra Deep Field-South 7 Ms observations, while the SFRs
and M <SUB>*</SUB> have been estimated by the CANDELS team through
spectral energy distribution fitting. The average BHAR is correlated
positively with both SFR and M <SUB>*</SUB>, and the BHAR-SFR and BHAR-M
<SUB>*</SUB> relations can both be described acceptably by linear
models with a slope of unity. However, BHAR appears to be correlated
more strongly with M <SUB>*</SUB> than SFR. This result indicates
that M <SUB>*</SUB> is the primary host-galaxy property related to
supermassive black hole (SMBH) growth, and the apparent BHAR-SFR
relation is largely a secondary effect due to the star-forming main
sequence. Among our sources, massive galaxies ({M}<SUB>* </SUB>≳
{10}<SUP>10</SUP>{M}<SUB>⊙ </SUB>) have significantly higher BHAR/SFR
ratios than less massive galaxies, indicating that the former have
higher SMBH fueling efficiency and/or higher SMBH occupation fraction
than the latter. Our results can naturally explain the observed
proportionality between {M}<SUB>{BH</SUB>} and M <SUB>*</SUB> for local
giant ellipticals and suggest that their {M}<SUB>{BH</SUB>}/{M}<SUB>*
</SUB> is higher than that of local star-forming galaxies. Among
local star-forming galaxies, massive systems might have higher
{M}<SUB>{BH</SUB>}/{M}<SUB>* </SUB> compared to dwarfs.
---------------------------------------------------------
Title: Central Engine and Host Galaxy of RXJ 1301.9+2747:
A Multiwavelength View of a Low-mass Black Hole Active Galactic
Nuclei with Ultra-soft X-Ray Emission
Authors: Shu, X. W.; Wang, T. G.; Jiang, N.; Wang, J. X.; Sun, L. M.;
Zhou, H. Y.
2017ApJ...837....3S Altcode: 2017arXiv170402886S
RXJ 1301.9+2747 is an optically identified very-low-mass AGN
candidate with {M}<SUB>{BH</SUB>}∼ 1× {10}<SUP>6</SUP> {M}<SUB>⊙
</SUB>, which shows extremely soft X-ray emission and unusual X-ray
variability in the form of short-lived flares. We present an analysis of
multiwavelength observations of RXJ 1301.9+2747 in order to study the
properties of the active nucleus and its host galaxy. The UV-to-X-ray
spectrum in the quiescent state can be well and self-consistently
described by a thermal and a Comptonized emission from the accretion
disk, with the black body dominating ∼70% of the X-rays in the 0.2-2
keV. The same model can describe the X-ray spectrum in the flare state,
but the Comptonized component becomes dominant (∼80%). The best
fit implies an Eddington ratio of ∼0.14 and a black-hole mass of
(1.7-2.8)× {10}<SUP>6</SUP> M <SUB>⊙</SUB>, in agreement with
the estimation from the optical data within errors. However, the
best-fitting model under predicts the optical flux for the HST point
source by a factor of ∼2. The excess of nuclear optical emission
could be attributed to a nuclear stellar cluster, which is frequently
seen in low-mass AGNs. The X-ray to optical spectral slope ({α
}<SUB>{ox</SUB>}) is lower than in most other active galaxies, which may
be attributed to intrinsically X-ray weakness due to very little hot
and optically thin coronal emission. We performed a pilot search for
weak or hidden broad emission lines using optical spectropolarimetry
observations, but no polarized broad lines are detected. The host
galaxy appears to be a disk galaxy with a boxy pseudobulge or nuclear
bar accounting for ∼15% of the total starlight, which is consistent
with the general characteristics of the host of low-mass AGNs.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Chandra Deep Field-South survey:
7Ms sources (Luo+, 2017)
Authors: Luo, B.; Brandt, W. N.; Xue, Y. Q.; Lehmer, B.; Alexander,
D. M.; Bauer, F. E.; Vito, F.; Yang, G.; Basu-Zych, A. R.; Comastri,
A.; Gilli, R.; Gu, Q. -S.; Hornschemeier, A. E.; Koekemoer, A.; Liu,
T.; Mainieri, V.; Paolillo, M.; Ranalli, P.; Rosati, P.; Schneider,
D. P.; Shemmer, O.; Smail, I.; Sun, M.; Tozzi, P.; Vignali, C.; Wang,
J. -X.
2017yCat..22280002L Altcode:
The 7Ms CDF-S contains 102 Chandra ACIS-I observations, with a total
cleaned exposure time of 6.727Ms, taken in four separate epochs of
time. The basic information on these observations is listed in Table
1. <P />There were 48 recent observations acquired between 2014 June
9 and 2016 March 24, which constitute the last 3Ms of exposure of
the 7Ms CDF-S. The first 1Ms of exposure consists of 11 observations
taken between 1999 and 2000 (Giacconi+ 2002, J/ApJS/139/369; Rosati+
2002ApJ...566..667R; Alexander+ 2003, J/AJ/126/539), the next 1Ms
of exposure consists of 12 observations taken in 2007 (Luo+ 2008,
J/ApJS/179/19), and another 2Ms of exposure includes 31 observations
in 2010 (Xue+ 2011, J/ApJS/195/10). <P />The total area covered by
the 7Ms CDF-S is 484.2arcmin<SUP>2</SUP>. <P />(3 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: 6Ms Chandra long-term analyses
of AGNs (Yang+, 2016)
Authors: Yang, G.; Brandt, W. N.; Luo, B.; Xue, Y. Q.; Bauer, F. E.;
Sun, M. Y.; Kim, S.; Schulze, S.; Zheng, X. C.; Paolillo, M.; Shemmer,
O.; Liu, T.; Schneider, D. P.; Vignali, C.; Vito, F.; Wang, J. -X.
2017yCat..18310145Y Altcode:
This work is based on the Chandra CDF-S data. The observations were
taken from 1999 October to 2015 January with a total observation time
of 5.7Ms. In total, there are 84 observations utilized with median
exposure time ~60ks. All of the 84 observations were performed using the
Advanced CCD Imaging Spectrometer imaging array (ACIS-I). See B. Luo
et al. 2016, in prep (L16) for more observation details. Sixty-eight
sources are selected with 649-11283 counts; the median number of counts
is 1399. <P />(1 data file).
---------------------------------------------------------
Title: The Chandra Deep Field-South Survey: 7 Ms Source Catalogs
Authors: Luo, B.; Brandt, W. N.; Xue, Y. Q.; Lehmer, B.; Alexander,
D. M.; Bauer, F. E.; Vito, F.; Yang, G.; Basu-Zych, A. R.; Comastri,
A.; Gilli, R.; Gu, Q. -S.; Hornschemeier, A. E.; Koekemoer, A.; Liu,
T.; Mainieri, V.; Paolillo, M.; Ranalli, P.; Rosati, P.; Schneider,
D. P.; Shemmer, O.; Smail, I.; Sun, M.; Tozzi, P.; Vignali, C.; Wang,
J. -X.
2017ApJS..228....2L Altcode: 2016arXiv161103501L
We present X-ray source catalogs for the ≈7 Ms exposure of the
Chandra Deep Field-South (CDF-S), which covers a total area of 484.2
arcmin<SUP>2</SUP>. Utilizing WAVDETECT for initial source detection and
ACIS Extract for photometric extraction and significance assessment,
we create a main source catalog containing 1008 sources that are
detected in up to three X-ray bands: 0.5-7.0 keV, 0.5-2.0 keV, and
2-7 keV. A supplementary source catalog is also provided, including 47
lower-significance sources that have bright ({K}<SUB>s</SUB>≤slant 23)
near-infrared counterparts. We identify multiwavelength counterparts
for 992 (98.4%) of the main-catalog sources, and we collect redshifts
for 986 of these sources, including 653 spectroscopic redshifts and
333 photometric redshifts. Based on the X-ray and multiwavelength
properties, we identify 711 active galactic nuclei (AGNs) from the
main-catalog sources. Compared to the previous ≈4 Ms CDF-S catalogs,
291 of the main-catalog sources are new detections. We have achieved
unprecedented X-ray sensitivity with average flux limits over the
central ≈1 arcmin<SUP>2</SUP> region of ≈1.9 × 10<SUP>-17</SUP>,
6.4 × 10<SUP>-18</SUP>, and 2.7 × 10<SUP>-17</SUP> erg cm<SUP>-2</SUP>
s<SUP>-1</SUP> in the three X-ray bands, respectively. We provide
cumulative number-count measurements observing, for the first time,
that normal galaxies start to dominate the X-ray source population at
the faintest 0.5-2.0 keV flux levels. The highest X-ray source density
reaches ≈50,500 deg<SUP>-2</SUP>, and 47% ± 4% of these sources
are AGNs (≈23,900 deg<SUP>-2</SUP>).
---------------------------------------------------------
Title: VizieR Online Data Catalog: LAMOST DR2 catalogs (Luo+, 2016)
Authors: Luo, A. -L.; Zhao, Y. -H.; Zhao, G.; Deng, L. -C.; Liu,
X. -W.; Jing, Y. -P.; Wang, G.; Zhang, H. -T.; Shi, J. -R.; Cui,
X. -Q.; Chu, Y. -Q.; Li, G. -P.; Bai, Z. -R.; Wu, Y.; Cai, Y.; Cao,
S. -Y.; Cao, Z. -H.; Carlin, J. L.; Chen, H. -Y.; Chen, J. -J.; Chen,
K. -X.; Chen, L.; Chen, X. -L.; Chen, X. -Y.; Chen, Y.; Christlieb,
N.; Chu, J. -R.; Cui, C. -Z.; Dong, Y. -Q.; Du, B.; Fan, D. -W.; Feng,
L.; Fu, J. -N.; Gao, P.; Gong, X. -F.; Gu, B. -Z.; Guo, Y. -X.; Han,
Z. -W.; He, B. -L.; Hou, J. -L.; Hou, Y. -H.; Hou, W.; Hu, H. -Z.; Hu,
N. -S.; Hu, Z. -W.; Huo, Z. -Y.; Jia, L.; Jiang, F. -H.; Jiang, X.;
Jiang, Z. -B.; Jin, G.; Kong, X.; Kong, X.; Lei, Y. -J.; Li, A. -H.;
Li, C. -H.; Li, G. -W.; Li, H. -N.; Li, J.; Li, Q.; Li, S.; Li, S. -S.;
Li, X. -N.; Li, Y.; Li, Y. -B.; Li, Y. -P.; Liang, Y.; Lin, C. -C.;
Liu, C.; Liu, G. -R.; Liu, G. -Q.; Liu, Z. -G.; Lu, W. -Z.; Luo, Y.;
Mao, Y. -D.; Newberg, H.; Ni, J. -J.; Qi, Z. -X.; Qi, Y. -J.; Shen,
S. -Y.; Shi, H. -M.; Song, J.; Song, Y. -H.; Su, D. -Q.; Su, H. -J.;
Tang, Z. -H.; Tao, Q. -S.; Tian, Y.; Wang, D.; Wang, D. -Q.; Wang,
F. -F.; Wang, G. -M.; Wang, H.; Wang, H. -C.; Wang, J.; Wang, J. -N.;
Wang, J. -L.; Wang, J. -P.; Wang, J. -X.; Wang, L.; Wang, M. -X.;
Wang, S. -G.; Wang, S. -Q.; Wang, X.; Wang, Y. -N.; Wang, Y.; Wang,
Y. -F.; Wang, Y. -F.; Wei, P.; Wei, M. -Z.; Wu, H.; Wu, K. -F.; Wu,
X. -B.; Wu, Y. -Z.; Xing, X. -Z.; Xu, L. -Z.; Xu, X. -Q.; Xu, Y.;
Yan, T. -S.; Yang, D. -H.; Yang, H. -F.; Yang, H. -Q.; Yang, M.; Yao,
Z. -Q.; Yu, Y.; Yuan, H.; Yuan, H. -B.; Yuan, H. -L.; Yuan, W. -M.;
Zhai, C.; Zhang, E. -P.; Zhang, H. -W.; Zhang, J. -N.; Zhang, L. -P.;
Zhang, W.; Zhang, Y.; Zhang, Y. -X.; Zhang, Z. -C.; Zhao, M.; Zhou,
F.; Zhou, X.; Zhu, J.; Zhu, Y. -T.; Zou, S. -C.; Zuo, F.
2016yCat.5149....0L Altcode:
There are a couple of corrections been made in this releasing:
<P />Recalculated all the errors of Teff, Logg, Fe/H and rv in the
AFGK catalog. Refer to the DR2 paper (in preparation) for details. <P
/>Compare to the previous internal releasing, some extra spectra has
been added into this version of releasing: STAR from 3,779,597 to
3,843,597, increased 63,923; GALAXY from 37,665 to 47,036, increased
9,371; QSO from 8,633 to 13,262, increased 4,629. <P />The major
contribution to this increasing is that we applied a new method to
reduce the data which previously was abandoned due to lack of standard
stars with high enough S/N. Refer to the paper 'LAMOST Spectrograph
Response Curves: Stability and Application to flux calibration'
(in preparation) for details. <P />There are also a small amount of
increasing is due to the correction of fiber flag, and to the eye
check work, etc. <P />(5 data files).
---------------------------------------------------------
Title: The deepest X-ray view of high-redshift galaxies: constraints
on low-rate black hole accretion
Authors: Vito, F.; Gilli, R.; Vignali, C.; Brandt, W. N.; Comastri,
A.; Yang, G.; Lehmer, B. D.; Luo, B.; Basu-Zych, A.; Bauer, F. E.;
Cappelluti, N.; Koekemoer, A.; Mainieri, V.; Paolillo, M.; Ranalli,
P.; Shemmer, O.; Trump, J.; Wang, J. X.; Xue, Y. Q.
2016MNRAS.463..348V Altcode: 2016MNRAS.tmp.1093V; 2016arXiv160802614V
We exploit the 7 Ms Chandra observations in the Chandra Deep Field-South
(CDF-S), the deepest X-ray survey to date, coupled with CANDELS/GOODS-S
data, to measure the total X-ray emission arising from 2076 galaxies at
3.5 ≤ z < 6.5. This aim is achieved by stacking the Chandra data
at the positions of optically selected galaxies, reaching effective
exposure times of ≥10<SUP>9</SUP>s. We detect significant (>3.7σ)
X-ray emission from massive galaxies at z ≈ 4. We also report the
detection of massive galaxies at z ≈ 5 at a 99.7 per cent confidence
level (2.7σ), the highest significance ever obtained for X-ray emission
from galaxies at such high redshifts. No significant signal is detected
from galaxies at even higher redshifts. The stacking results place
constraints on the BHAD associated with the known high-redshift galaxy
samples, as well as on the SFRD at high redshift, assuming a range of
prescriptions for X-ray emission due to X- ray binaries. We find that
the X-ray emission from our sample is likely dominated by processes
related to star formation. Our results show that low-rate mass accretion
on to SMBHs in individually X-ray-undetected galaxies is negligible,
compared with the BHAD measured for samples of X-ray detected AGN, for
cosmic SMBH mass assembly at high redshift. We also place, for the first
time, constraints on the faint-end of the AGN X-ray luminosity function
(logL<SUB>X</SUB> ∼ 42) at z > 4, with evidence for fairly flat
slopes. The implications of all of these findings are discussed in
the context of the evolution of the AGN population at high redshift.
---------------------------------------------------------
Title: Long-term X-Ray Variability of Typical Active Galactic Nuclei
in the Distant Universe
Authors: Yang, G.; Brandt, W. N.; Luo, B.; Xue, Y. Q.; Bauer, F. E.;
Sun, M. Y.; Kim, S.; Schulze, S.; Zheng, X. C.; Paolillo, M.; Shemmer,
O.; Liu, T.; Schneider, D. P.; Vignali, C.; Vito, F.; Wang, J. -X.
2016ApJ...831..145Y Altcode: 2016arXiv160808224Y
We perform long-term (≈15 years, observed-frame) X-ray variability
analyses of the 68 brightest radio-quiet active galactic nuclei (AGNs)
in the 6 Ms Chandra Deep Field-South survey; the majority are in the
redshift range of 0.6-3.1, providing access to penetrating rest-frame
X-rays up to ≈10-30 keV. Of the 68 sources, 24 are optical spectral
type I AGNs, and the rest (44) are type II AGNs. The timescales probed
in this work are among the longest for X-ray variability studies
of distant AGNs. Photometric analyses reveal widespread photon flux
variability: 90% of AGNs are variable above a 95% confidence level,
including many X-ray obscured AGNs and several optically classified
type II quasars. We characterize the intrinsic X-ray luminosity
({L}<SUB>{{X</SUB>}}) and absorption ({N}<SUB>{{H</SUB>}}) variability
via spectral fitting. Most (74%) sources show {L}<SUB>{{X</SUB>}}
variability; the variability amplitudes are generally smaller for
quasars. A Compton-thick candidate AGN shows variability of its
high-energy X-ray flux, indicating the size of reflecting material to be
≲0.3 pc. {L}<SUB>{{X</SUB>}} variability is also detected in a broad
absorption line quasar. The {N}<SUB>{{H</SUB>}} variability amplitude
for our sample appears to rise as time separation increases. About
16% of sources show {N}<SUB>{{H</SUB>}} variability. One source
transitions from an X-ray unobscured to obscured state, while its
optical classification remains type I; this behavior indicates the
X-ray eclipsing material is not large enough to obscure the whole
broad-line region.
---------------------------------------------------------
Title: Probing AGN Accretion History Through X-Ray Variability
Authors: Paolillo, Maurizio; Papadakis, I.; Brandt, W. N.; Xue, Y. Q.;
Luo, B.; Tozzi, P.; Shemmer, O.; Allevato, V.; Bauer, F.; Koekemoer,
A.; Vignali, C.; Vito, F.; Yang, G.; Wang, J. X.; Zheng, X.
2016agnt.confE..39P Altcode:
I will present recent results on AGN variability in the CDFS
survey. Using over 10 years of X-ray monitoring and comparison with
local AGNs we are able to constrain the variability dependence on BH
mass and accreton rate, and use it to trace the accretion hisory of
the AGN population up to z=3.
---------------------------------------------------------
Title: The Deepest X-Ray View Of High-Redshift Galaxies: Constraints
On Low-Rate Black-Hole Accretion
Authors: Vito, Fabio; Gilli, R.; Vignali, C.; Brandt, W. N.; Comastri,
A.; Yang, G.; Lehmer, B. D.; Luo, B.; Basu-Zych, A.; Bauer, F. E.;
Cappelluti, N.; Koekemoer, A.; Mainieri, V.; Paolillo, M.; Ranalli,
P.; Shemmer, O.; Trump, J.; Wang, J. X.
2016agnt.confE..41V Altcode:
We exploit the new 7 Ms Chandra observations in the CDF-S, the deepest
X-ray survey to date, coupled with CANDELS/GOODS- S data, to measure
the total X-ray emission arising from 2000 galaxies at 3.5 < z
< 6.5. This aim is achieved by stacking the Chandra data at the
positions of optically selected galaxies, reaching effective exposure
times of >=10^9 s. We detect X-ray emission from z ∼ 4 galaxies
at 3 ∼ 5sigma, while no significant signal is detected from galaxies
at higher redshifts. The stacking results are used to estimate the
black hole accretion rate density (BHAD) and star -formation rate
density (SFRD) at high redshift, assuming a range of prescriptions
for X-ray emission due to X-ray binaries. We find that X-ray emission
from our sample is likely dominated by processes related to star
formation. Our results show that low-rate mass accretion onto SMBHs in
individually X-ray-undetected galaxies is negligible, compared with
the BHAD measured for samples of X-ray detected AGN, for cosmic SMBH
mass assembly at high redshift. We also place, for the first time,
constraints on the faint-end of the AGN X- ray luminosity function
(logLX ∼ 42) at z > 4, with evidence for fairly flat slopes.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Evolution of ~6Ms CDF-S galaxies
(Lehmer+, 2016)
Authors: Lehmer, B. D.; Basu-Zych, A. R.; Mineo, S.; Brandt, W. N.;
Eufrasio, R. T.; Fragos, T.; Hornschemeier, A. E.; Luo, B.; Xue,
Y. Q.; Bauer, F. E.; Gilfanov, M.; Ranalli, P.; Schneider, D. P.;
Shemmer, O.; Tozzi, P.; Trump, J. R.; Vignali, C.; Wang, J. -X.;
Yukita, M.; Zezas, A.
2016yCat..18250007L Altcode:
We began with an initial sample of 32508 galaxies in the Great
Observatories Origins Deep Survey South (GOODS-S) footprint as presented
in Section 2 of Xue et al. (2012, J/ApJ/758/129). We cut our initial
sample to the 24941 objects that were within 7' of the mean ~6Ms CDF-S
aimpoint, a region where the Chandra point-spread function (PSF) is
sharpest and the corresponding X-ray sensitivity is highest. See text
for further explanations. <P />(2 data files).
---------------------------------------------------------
Title: The Evolution of Normal Galaxy X-Ray Emission through Cosmic
History: Constraints from the 6 MS Chandra Deep Field-South
Authors: Lehmer, B. D.; Basu-Zych, A. R.; Mineo, S.; Brandt, W. N.;
Eufrasio, R. T.; Fragos, T.; Hornschemeier, A. E.; Luo, B.; Xue,
Y. Q.; Bauer, F. E.; Gilfanov, M.; Ranalli, P.; Schneider, D. P.;
Shemmer, O.; Tozzi, P.; Trump, J. R.; Vignali, C.; Wang, J. -X.;
Yukita, M.; Zezas, A.
2016ApJ...825....7L Altcode: 2016arXiv160406461L
We present measurements of the evolution of normal-galaxy X-ray
emission from z\quad ≈ 0-7 using local galaxies and galaxy samples
in the ≈6 Ms Chandra Deep Field-South (CDF-S) survey. The majority
of the CDF-S galaxies are observed at rest-frame energies above 2
keV, where the emission is expected to be dominated by X-ray binary
(XRB) populations; however, hot gas is expected to provide small
contributions to the observed-frame ≲1 keV emission at z ≲
1. We show that a single scaling relation between X-ray luminosity
({L}<SUB>{{X</SUB>}}) and star-formation rate (SFR) literature,
is insufficient for characterizing the average X-ray emission at all
redshifts. We establish that scaling relations involving not only SFR,
but also stellar mass ({M}<SUB>\star </SUB>) and redshift, provide
significantly improved characterizations of the average X-ray emission
from normal galaxy populations at z\quad ≈ 0-7. We further provide the
first empirical constraints on the redshift evolution of X-ray emission
from both low-mass XRB (LMXB) and high-mass XRB (HMXB) populations and
their scalings with {M}<SUB>\star </SUB> and SFR, respectively. We
find {L}<SUB>2-10{keV</SUB>}(LMXB)/{M}<SUB>\star </SUB>\propto
{(1+z)}<SUP>2-3</SUP> and {L}<SUB>2-10{keV</SUB>}(HMXB)/SFR \propto
\quad (1+z), and show that these relations are consistent with XRB
population-synthesis model predictions, which attribute the increase in
LMXB and HMXB scaling relations with redshift as being due to declining
host galaxy stellar ages and metallicities, respectively. We discuss
how emission from XRBs could provide an important source of heating
to the intergalactic medium in the early universe, exceeding that of
active galactic nuclei.
---------------------------------------------------------
Title: Observations of Magnetic Flux-rope Oscillation during the
Precursor Phase of a Solar Eruption
Authors: Zhou, G. P.; Zhang, J.; Wang, J. X.
2016ApJ...823L..19Z Altcode:
Based on combined observations from the Interface Region Imaging
Spectrograph (IRIS) spectrometer with the coronal emission line
of Fe xxi at 1354.08 Å and SDO/AIA images in multiple passbands,
we report the finding of the precursor activity manifested as the
transverse oscillation of a sigmoid, which is likely a pre-existing
magnetic flux rope (MFR), that led to the onset of an X class flare
and a fast halo coronal mass ejection (CME) on 2014 September 10. The
IRIS slit is situated at a fixed position that is almost vertical
to the main axis of the sigmoid structure that has a length of about
1.8 × 10<SUP>5</SUP> km. This precursor oscillation lasts for about
13 minutes in the MFR and has velocities in the range of [-9, 11] km
s<SUP>-1</SUP> and a period of ∼280 s. Our analysis, which is based
on the temperature, density, length, and magnetic field strength of
the observed sigmoid, indicates that the nature of the oscillation is a
standing wave of fast magnetoacoustic kink mode. We further find that
the precursor oscillation is excited by the energy released through
an external magnetic reconnection between the unstable MFR and the
ambient magnetic field. It is proposed that this precursor activity
leads to the dynamic formation of a current sheet underneath the MFR
that subsequently reconnects to trigger the onset of the main phase
of the flare and the CME.
---------------------------------------------------------
Title: Identification of z ≳ 2 Herschel 500 μM Sources Using
Color Deconfusion
Authors: Shu, X. W.; Elbaz, D.; Bourne, N.; Schreiber, C.; Wang, T.;
Dunlop, J. S.; Fontana, A.; Leiton, R.; Pannella, M.; Okumura, K.;
Michałowski, M. J.; Santini, P.; Merlin, E.; Buitrago, F.; Bruce,
V. A.; Amorin, R.; Castellano, M.; Derriere, S.; Comastri, A.;
Cappelluti, N.; Wang, J. X.; Ferguson, H. C.
2016ApJS..222....4S Altcode: 2015arXiv151200167S
We present a new method to search for candidate z ≳ 2 Herschel 500
μm sources in the Great Observatories Origins Deep Survey-North field
using a S<SUB>500 μm</SUB>/S<SUB>24 μm</SUB> “color deconfusion”
technique. Potential high-z sources are selected against low-redshift
ones from their large 500 to 24 μm flux density ratios. By effectively
reducing the contribution from low-redshift populations to the
observed 500 μm emission, we are able to identify counterparts to
high-z 500 μm sources whose 24 μm fluxes are relatively faint. The
recovery of known z ≳ 4 starbursts confirms the efficiency of this
approach in selecting high-z Herschel sources. The resulting sample
consists of 34 dusty star-forming galaxies at z ≳ 2. The inferred
infrared luminosities are in the range 1.5 × 10<SUP>12</SUP>-1.8 ×
10<SUP>13</SUP> L<SUB>⊙</SUB>, corresponding to dust-obscured star
formation rates (SFRs) of ∼260-3100 M<SUB>⊙</SUB> yr<SUP>-1</SUP>
for a Salpeter initial mass function. Comparison with previous SCUBA 850
μ {{m}}-selected galaxy samples shows that our method is more efficient
at selecting high-z dusty galaxies, with a median redshift of z=3.07+/-
0.83 and with 10 of the sources at z ≳ 4. We find that at a fixed
luminosity, the dust temperature is ∼5 K cooler than that expected
from the {T}<SUB>d</SUB>-{L}<SUB>{{IR</SUB>}} relation at z\quad ≲ 1,
though different temperature selection effects should be taken into
account. The radio-detected subsample (excluding three strong active
galactic nucleus) follows the far-infrared (far-IR)/radio correlation at
lower redshifts, and no evolution with redshift is observed out to z∼
5, suggesting that the far-IR emission is star formation dominated. The
contribution of the high-z Herschel 500 μm sources to the cosmic SFR
density is comparable to that of (sub)millimeter galaxy populations at
z∼ 2.5 and at least 40% of the extinction-corrected UV samples at
z∼ 4. Further investigation into the nature of these high-z dusty
galaxies will be crucial for our understanding of the star formation
histories and the buildup of stellar mass at the earliest cosmic epochs.
---------------------------------------------------------
Title: Photometric Redshifts in the Hawaii-Hubble Deep Field-North
Authors: Yang, G.; Xue, Y. Q.; Luo, B.; Brandt, W. N.; Alexander,
D. M.; Bauer, F. E.; Cui, W.; Kong, X.; Lehmer, B. D.; Wang, J. -X.;
Wu, X. -B.; Yuan, F.; Yuan, Y. -F.; Zhou, H. Y.
2016IAUS..319...56Y Altcode:
We derive z <SUB>phot</SUB> for sources in the entire (~0.4
deg<SUP>2</SUP>) H-HDF-N field with the EAzY code, based on PSF-matched
broad-band (U band to IRAC 4.5 μm) photometry. Our catalog consists
of a total of 131,678 sources. We find σ<SUB>NMAD</SUB> = 0.029 for
non-X-ray sources. We also classify each object as a star or galaxy
through SED fitting. Furthermore, we match our catalog with the 2 Ms
CDF-N main X-ray catalog. For the 462 matched non-stellar X-ray sources,
we improve their z <SUB>phot</SUB> quality (σ<SUB>NMAD</SUB> = 0.035)
by adding three additional AGN templates. We make our photometry and
z <SUB>phot</SUB> catalog publicly available.
---------------------------------------------------------
Title: VizieR Online Data Catalog: LAMOST DR1 catalogs (Luo+, 2015)
Authors: Luo, A. -L.; Zhao, Y. -H.; Zhao, G.; Deng, L. -C.; Liu,
X. -W.; Jing, Y. -P.; Wang, G.; Zhang, H. -T.; Shi, J. -R.; Cui,
X. -Q.; Chu, Y. -Q.; Li, G. -P.; Bai, Z. -R.; Wu, Y.; Cai, Y.; Cao,
S. -Y.; Cao, Z. -H.; Carlin, J. L.; Chen, H. -Y.; Chen, J. -J.; Chen,
K. -X.; Chen, L.; Chen, X. -L.; Chen, X. -Y.; Chen, Y.; Christlieb,
N.; Chu, J. -R.; Cui, C. -Z.; Dong, Y. -Q.; Du, B.; Fan, D. -W.; Feng,
L.; Fu, J. -N.; Gao, P.; Gong, X. -F.; Gu, B. -Z.; Guo, Y. -X.; Han,
Z. -W.; He, B. -L.; Hou, J. -L.; Hou, Y. -H.; Hou, W.; Hu, H. -Z.; Hu,
N. -S.; Hu, Z. -W.; Huo, Z. -Y.; Jia, L.; Jiang, F. -H.; Jiang, X.;
Jiang, Z. -B.; Jin, G.; Kong, X.; Kong, X.; Lei, Y. -J.; Li, A. -H.;
Li, C. -H.; Li, G. -W.; Li, H. -N.; Li, J.; Li, Q.; Li, S.; Li, S. -S.;
Li, X. -N.; Li, Y.; Li, Y. -B.; Li, Y. -P.; Liang, Y.; Lin, C. -C.;
Liu, C.; Liu, G. -R.; Liu, G. -Q.; Liu, Z. -G.; Lu, W. -Z.; Luo,
Y.; Mao, Y. -D.; Newberg, H.; Ni, J. -J.; Qi, Z. -X.; Qi, Y. -J.;
Shen, S. -Y.; Shi, H. -M.; Song, J.; Song, Y. -H.; Su, D. -Q.; Su,
H. -J.; Tang, Z. -H.; Tao, Q. -S.; Tian, Y.; Wang, D.; Wang, D. -Q.;
Wang, F. -F.; Wang, G. -M.; Wang, H.; Wang, H. -C.; Wang, J.; Wan!,
G. J. -N.; Wang, J. -L.; Wang, J. -P.; Wang, J. -X.; Wang, L.; Wang,
M. -X.; Wang, S. -G.; Wang, S. -Q.; Wang, X.; Wang, Y. -N.; Wang, Y.;
Wang, Y. -F.; Wang, Y. -F.; Wei, P.; Wei, M. -Z.; Wu, H.; Wu, K. -F.;
Wu, X. -B.; Wu, Y. -Z.; Xing, X. -Z.; Xu, L. -Z.; Xu, X. -Q.; Xu, Y.;
Yan, T. -S.; Yang, D. -H.; Yang, H. -F.; Yang, H. -Q.; Yang, M.; Yao,
Z. -Q.; Yu, Y.; Yuan, H.; Yuan, H. -B.; Yuan, H. -L.; Yuan, W. -M.;
Zhai, C.; Zhang, E. -P.; Zhang, H. -W.; Zhang, J. -N.; Zhang, L. -P.;
Zhang, W.; Zhang, Y.; Zhang, Y. -X.; Zhang, Z. -C.; Zhao, M.; Zhou,
F.; Zhou, X.; Zhu, J.; Zhu, Y. -T.; Zou, S. -C.; Zuo, F.
2015yCat.5146....0L Altcode:
The LAMOST general catalog includes 717469 objects obtained from the
LAMOST pilot survey, which contain 648746 stars, 2723 galaxies, 621
quasars and 65406 unknown objects, and 1487200 objects obtained from
the LAMOST general survey, which contain 1295583 stars, 9359 galaxies,
4396 quasars and 177862 unknown objects, so this catalog totally
includes 2204696 objects including 1,944,329 stars, 12082 galaxies,
5017 quasars and 243268 unknown objects. In this catalog, there are
1186132 objects with SNR of g band larger than 10, 1680794 objects with
SNR of i band larger than 10, and 1746202 objects with SNR of g band
larger than 10 and SNR of i band larger than 10. <P />(6 data files).
---------------------------------------------------------
Title: Does the Variation of Solar Intra-network Horizontal Field
Follow Sunspot Cycle?
Authors: Jin, C. L.; Wang, J. X.
2015ApJ...807...70J Altcode:
The ubiquitousness of the solar inter-network horizontal magnetic
field has been revealed by space-borne observations with high spatial
resolution and polarization sensitivity. However, no consensus has
been achieved on the origin of the horizontal field among solar
physicists. For a better understanding, in this study, we analyze
the cyclic variation of the inter-network horizontal field by using
the spectro-polarimeter observations provided by the Solar Optical
Telescope on board Hinode, covering the interval from 2008 April
to 2015 February. The method of wavelength integration is adopted to
achieve a high signal-to-noise ratio. It is found that from 2008 to 2015
the inter-network horizontal field does not vary when solar activity
increases, and the average flux density of the inter-network horizontal
field is 87 ± 1 G, In addition, the imbalance between horizontal and
vertical fields also keeps invariant within the scope of deviation,
i.e., 8.7 ± 0.5, from the solar minimum to maximum of solar cycle
24. This result confirms that the inter-network horizontal field is
independent of the sunspot cycle. The revelation favors the idea that
a local dynamo is creating and maintaining the solar inter-network
horizontal field.
---------------------------------------------------------
Title: VizieR Online Data Catalog: SWXCS III. Cluster catalog from
2005-2012 Swift data (Liu+, 2015)
Authors: Liu, T.; Tozzi, P.; Tundo, E.; Moretti, A.; Rosati, P.;
Wang, J. -X.; Tagliaferri, G.; Campana, S.; Giavalisco, M.
2015yCat..22160028L Altcode:
From the entire Swift XRT archive in the period 2005 February-2012
November, we select all the fields that can be used to build an
unbiased, serendipitous X-ray cluster catalog. <P />(2 data files).
---------------------------------------------------------
Title: VizieR Online Data Catalog: Photometric redshifts in the
Hawaii-HDF-N (Yang+, 2014)
Authors: Yang, G.; Xue, Y. Q.; Luo, B.; Brandt, W. N.; Alexander,
D. M.; Bauer, F. E.; Cui, W.; Kong, X.; Lehmer, B. D.; Wang, J. -X.;
Wu, X. -B.; Yuan, F.; Yuan, Y. -F.; Zhou, H. Y.
2015yCat..22150027Y Altcode:
We collect the U-, B-, V-, R-, I-, z'-, and HK'-band images from
Capak+, 2004, J/AJ/127/180, the J- and H-band images from Keenan et
al. (2010ApJS..186...94K), and the Ks-band image from Wang et al. (2010,
J/ApJS/187/251), respectively. We also make use of an independently
observed z'-band image from Ouchi et al. (2009ApJ...706.1136O). The
IRAC 3.6, 4.5, 5.8, and 8.0um images were obtained from the Spitzer
Heritage Archive, while another set of IRAC 3.6 and 4.5um images were
taken from the Spitzer Extended Deep Survey (SEDS) presented in Ashby
et al. (2013, J/ApJ/769/80). <P />(1 data file).
---------------------------------------------------------
Title: Photometric Redshifts in the Hawaii-Hubble Deep Field-North
(H-HDF-N)
Authors: Yang, G.; Xue, Y. Q.; Luo, B.; Brandt, W. N.; Alexander,
D. M.; Bauer, F. E.; Cui, W.; Kong, X.; Lehmer, B. D.; Wang, J. -X.;
Wu, X. -B.; Yuan, F.; Yuan, Y. -F.; Zhou, H. Y.
2014ApJS..215...27Y Altcode: 2014arXiv1410.6860Y
We derive photometric redshifts (z <SUB>phot</SUB>) for sources in the
entire (~0.4 deg<SUP>2</SUP>) Hawaii-Hubble Deep Field-North (H-HDF-N)
field with the EAzY code, based on point-spread-function-matched
photometry of 15 broad bands from the ultraviolet (U band) to
mid-infrared (IRAC 4.5 μm). Our catalog consists of a total of 131,678
sources. We evaluate the z <SUB>phot</SUB> quality by comparing z
<SUB>phot</SUB> with spectroscopic redshifts (z <SUB>spec</SUB>) when
available, and find a value of normalized median absolute deviation
σ<SUB>NMAD</SUB> = 0.029 and an outlier fraction of 5.5% (outliers are
defined as sources having |z<SUB>phot</SUB> - z<SUB>spec</SUB> |/(1 +
z<SUB>spec</SUB> ) > 0.15) for non-X-ray sources. More specifically,
we obtain σ<SUB>NMAD</SUB> = 0.024 with 2.7% outliers for sources
brighter than R = 23 mag, σ<SUB>NMAD</SUB> = 0.035 with 7.4% outliers
for sources fainter than R = 23 mag, σ<SUB>NMAD</SUB> = 0.026 with 3.9%
outliers for sources having z < 1, and σ<SUB>NMAD</SUB> = 0.034 with
9.0% outliers for sources having z > 1. Our z <SUB>phot</SUB> quality
shows an overall improvement over an earlier z <SUB>phot</SUB> work
that focused only on the central H-HDF-N area. We also classify each
object as a star or galaxy through template spectral energy distribution
fitting and complementary morphological parameterization, resulting
in 4959 stars and 126,719 galaxies. Furthermore, we match our catalog
with the 2 Ms Chandra Deep Field-North main X-ray catalog. For the
462 matched non-stellar X-ray sources (281 having z <SUB>spec</SUB>),
we improve their z <SUB>phot</SUB> quality by adding three additional
active galactic nucleus templates, achieving σ<SUB>NMAD</SUB> =
0.035 and an outlier fraction of 12.5%. We make our catalog publicly
available presenting both photometry and z <SUB>phot</SUB>, and provide
guidance on how to make use of our catalog.
---------------------------------------------------------
Title: The Swift X-ray Cluster Survey
Authors: Moretti, A.; Wang, J. X.; Liu, T.; Tundo, E.; Giavalisco,
M.; Liu, T.; Tozzi, P.; Campana, S.; Tagliaferri, G.
2014styd.confE..43M Altcode: 2014PoS...233E..43M
No abstract at ADS
---------------------------------------------------------
Title: Variation of the solar magnetic flux spectrum during solar
cycle 23
Authors: Jin, C. L.; Wang, J. X.
2014JGRA..119...11J Altcode: 2013arXiv1312.5816J
By using the unique database of Solar and Heliospheric
Observatory/Michelson Doppler Imager full disk magnetograms from
September 1996 to January 2011, covering the entire solar cycle 23,
we analyze the time-variability of the solar magnetic flux spectrum
and study the properties of extended minimum of cycle 23. We totally
identify 11.5 million magnetic structures. It has been revealed
that magnetic features with different magnetic fluxes exhibit
different cycle behaviors. The magnetic features with flux larger
than 4.0×10<SUP>19</SUP> Mx, which cover solar active regions and
strong network features, show exactly the same variation as sunspots;
however, the remaining 82% magnetic features which cover the majority of
network elements show anti-phase variation with sunspots. We select a
criterion that the monthly sunspot number is less than 20 to represent
the Sun's low activity status. Then we find the extended minimum of
cycle 23 is characterized by the long duration of low activity status,
but the magnitude of magnetic flux in this period is not lower than
previous cycle. Both the duration of low activity status and the minimum
activity level defined by minimum sunspot number show a century period
approximately. The extended minimum of cycle 23 shows similarities
with solar cycle 11, which preceded the mini-maxima in later solar
cycles. This similarity is suggestive that the solar cycles following
cycle 23 are likely to have low activity.
---------------------------------------------------------
Title: Formation and disappearance of a filament
Authors: Zhou, G. P.; Wang, J. X.; Tsuneta, S.
2013IAUS..294..593Z Altcode:
A continuous observations near an small active region (AR) NOAA 10976
by the Solar Optical Telescope (SOT) and X-Ray Telescope (XRT) on board
the Hinode satellite during Dec. 02 2007 from 15:50 UT to 19:59 UT. We
observed that: (a) the filament formed by merging parallel fibrils into
a twist structure. (b) the filament faded by reconnecting among its
own loop structures, or being stripped into pieces.These process are
always preceded by the brightening. (c) for the disappearance of the
filament, it has close correlation with the activity, like untwisting
or expanding, of its corresponding X-ray bright rope.
---------------------------------------------------------
Title: The Swift X-Ray Cluster Survey
Authors: Liu, T.; Tozzi, P.; Moretti, A.; Tundo, E.; Rosati, P.;
Borgani, S.; Tagliaferri, G.; Capana, S.; Fugazza, D.; D'Avanzo, P.;
Wang, J. -X.; Guglielmetti, F.
2013tcec.confE..28L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: EXSdetect: an end-to-end software for extended source detection
in X-ray images: application to Swift-XRT data
Authors: Liu, T.; Tozzi, P.; Tundo, E.; Moretti, A.; Wang, J. -X.;
Rosati, P.; Guglielmetti, F.
2013A&A...549A.143L Altcode: 2012arXiv1212.4038L
<BR /> Aims: We present a stand-alone software (named EXSdetect)
for the detection of extended sources in X-ray images. Our goal is to
provide a flexible tool capable of detecting extended sources down to
the lowest flux levels attainable within instrumental limitations,
while maintaining robust photometry, high completeness, and low
contamination, regardless of source morphology. EXSdetect was developed
mainly to exploit the ever-increasing wealth of archival X-ray data,
but is also ideally suited to explore the scientific capabilities of
future X-ray facilities, with a strong focus on investigations of
distant groups and clusters of galaxies. <BR /> Methods: EXSdetect
combines a fast Voronoi tessellation code with a friends-of-friends
algorithm and an automated deblending procedure. The values of key
parameters are matched to fundamental telescope properties such as
angular resolution and instrumental background. In addition, the
software is designed to permit extensive tests of its performance
via simulations of a wide range of observational scenarios. <BR />
Results: We applied EXSdetect to simulated data fields modeled to
realistically represent the Swift X-ray Cluster Survey (SXCS), which
is based on archival data obtained by the X-ray telescope onboard the
Swift satellite. We achieve more than 90% completeness for extended
sources comprising at least 80 photons in the 0.5-2 keV band, a limit
that corresponds to 10<SUP>-14</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP>
for the deepest SXCS fields. This detection limit is comparable to the
one attained by the most sensitive cluster surveys conducted with much
larger X-ray telescopes. While evaluating the performance of EXSdetect,
we also explored the impact of improved angular resolution and discuss
the ideal properties of the next generation of X-ray survey missions. <P
/>The Phyton code EXSdetect is available on the SXCS website <A
href="http://adlibitum.oats.inaf.it/sxcs">http://adlibitum.oats.inaf.it/sxcs</A>
---------------------------------------------------------
Title: Solar Intranetwork Magnetic Elements: Intrinsically Weak
or Strong?
Authors: Jin, C. L.; Wang, J. X.; Xie, Z. X.
2012SoPh..280...51J Altcode: 2012SoPh..tmp..151J
The high spatial resolution observation of a quiet region taken with
the Solar Optical Telescope/Spectro-Polarimeter aboard the Hinode
spacecraft is analyzed. Based on the Milne-Eddington atmospheric
model, the vector magnetic field of the quiet region is derived by
fitting the full Stokes profiles of the Fe I 630 nm line pair. We
extract intranetwork (IN) region from the quiet region and identify
5058 IN magnetic elements, and study their magnetic properties. As a
comparison, the magnetic properties of network (NT) region are also
analyzed. The main results are as follows. i) The IN area displays a
predominance of weak (hecto-gauss) field concentration, i.e., 99.8 %
of IN area shows the weak field. Moreover, the vector magnetic field
exhibits concentration toward horizontal direction. However, for
the NT region, we discover the coexistence of weak field and strong
(kilo-gauss, kG) field. In the IN and NT regions, the filling factor
shows almost the same probability distribution function with the peak
at about 0.28. ii) All IN magnetic elements show field strength less
than 1 kG. However, some NT elements display the coexistence of weak
field and strong field. Regardless of NT or IN elements, about 20 %
of elements lies in the Doppler blue-shift region. Our results imply
that not all magnetic elements lie in the down-draft sites.
---------------------------------------------------------
Title: Quantifying solar superactive regions with vector magnetic
field observations
Authors: Chen, A. Q.; Wang, J. X.
2012A&A...543A..49C Altcode: 2012arXiv1205.6533C
Context. The vector magnetic field characteristics of superactive
regions (SARs) hold the key for understanding why SARs are extremely
active and provide the guidance in space weather prediction. <BR />
Aims: We aim to quantify the characteristics of SARs using the vector
magnetograms taken by the Solar Magnetic Field Telescope at Huairou
Solar Observatory Station. <BR /> Methods: The vector magnetic field
characteristics of 14 SARs in solar cycles 22 and 23 were analyzed
using the following four parameters: 1) the magnetic flux imbalance
between opposite polarities; 2) the total photospheric free magnetic
energy; 3) the length of the magnetic neutral line with its steep
horizontal magnetic gradient; and 4) the area with strong magnetic
shear. Furthermore, we selected another eight large and inactive active
regions (ARs), which are called fallow ARs (FARs), to compare them
with the SARs. <BR /> Results: We found that most of the SARs have
a net magnetic flux higher than 7.0 × 10<SUP>21</SUP> Mx, a total
photospheric free magnetic energy higher than 1.0 × 10<SUP>24</SUP>
erg cm<SUP>-1</SUP>, a magnetic neutral line with a steep horizontal
magnetic gradient (≥300 G Mm<SUP>-1</SUP>) longer than 30 Mm, and
an area with strong magnetic shear (shear angle ≥ 80°) greater
than 100 Mm<SUP>2</SUP>. In contrast, the values of these parameters
for the FARs are mostly very low. The Pearson χ<SUP>2</SUP> test was
used to examine the significance of the difference between the SARs
and FARs, and the results indicate that these two types of ARs can
be fairly distinguished by each of these parameters. The significance
levels are 99.55%, 99.98%, 99.98%, and 99.96%, respectively. However,
no single parameter can distinguish them perfectly. Therefore we
propose a composite index based on these parameters, and find that
the distinction between the two types of ARs is also significant with
a significance level of 99.96%. These results are useful for a better
physical understanding of the SAR and FAR.
---------------------------------------------------------
Title: Sun's small-scale magnetic field : from quiet region to
polar region
Authors: Jin, C. L.; Wang, J. X.; Zhao, M.
2012EAS....55...15J Altcode:
In this contribution, we present our recent effort in understanding
the solar small-scale magnetic field. Firstly, with the unique
data from MDI/SOHO in an interval embodying solar cycle 23, we find
three categories of small-scale magnetic elements, and their number
variations shows no correlation, anti-correlation and correlation
with sunspots, respectively. The possible sources for the three
categories of small-scale magnetic elements are discussed. Secondly,
by the observations from SOT on board Hinode, we study the properties
of vector magnetic field in quiet Sun. The following results are
summarized. (1) Two categories of horizontal magnetic elements are
disclosed, and most of horizontal elements are associate with the
emergence of U-loop. (2) The magnetic field of quiet region is obviously
non-potential. The filigrees and network bright points are characterized
by strong longitudinal field, large electric helicity and free energy
density. (3) For quiet region, the intra-network region displays a
predominance of weak field concentration, but network region shows
the coexisting of weak field with strong field; For polar region,
the strong field occupies 6.7% of the region. (4) On quiet region,
the magnetic field mainly resides in the inter-granular lanes. By the
observation, we reconstruct an average granular model, for which the
detailed distributions of vector fields, Doppler velocity and intensity
are obtained.
---------------------------------------------------------
Title: Revision of Solar Spicule Classification
Authors: Zhang, Y. Z.; Shibata, K.; Wang, J. X.; Mao, X. J.; Matsumoto,
T.; Liu, Y.; Su, J. T.
2012ApJ...750...16Z Altcode: 2012arXiv1202.4518Z
Solar spicules are the fundamental magnetic structures in the
chromosphere and may play a key role in channeling the chromosphere and
corona. Recently, it was suggested by De Pontieu et al. that there were
two types of spicules with very different dynamic properties, which were
detected by the space-time plot technique in the Ca II H line (3968 Å)
wavelength from Hinode/Solar Optical Telescope observations. A "Type
I" spicule with a 3-7-minute lifetime undergoes a cycle of upward and
downward motions; by contrast, a "Type II" spicule fades away within
dozens of seconds without a descending phase. We are motivated by the
fact that for a spicule with complicated three-dimensional motion the
space-time plot, which is made through a slit on a fixed position, could
not match the spicule behavior all the time and might lose its real life
story. By revisiting the same data sets, we identify and trace 105 and
102 spicules in the quiet Sun (QS) and coronal hole (CH), respectively,
and obtain their statistical dynamic properties. First, we have not
found a single convincing example of "Type II" spicules. Second, more
than 60% of the identified spicules in each region show a complete
cycle, i.e., the majority are "Type I" spicules. Third, the lifetimes
of the spicules in the QS and CH are 148 s and 112 s, respectively,
but there is no fundamental lifetime difference between the spicules
in the QS and CH reported earlier. Therefore, the suggestion of coronal
heating by "Type II" spicules should be taken with caution.
---------------------------------------------------------
Title: A Possible Ultra Strong and Broad Fe Kα Emission Line in
Seyfert 2 Galaxy IRAS 00521-7054
Authors: Tan, Y.; Wang, J. X.; Shu, X. W.; Zhou, Youyuan
2012ApJ...747L..11T Altcode: 2012arXiv1202.0400T
We present XMM-Newton spectra of the Seyfert 2 Galaxy IRAS 00521-7054. A
strong feature at ~6 keV (observer's frame) can be formally fitted with
a strong (EW = 1.3 ± 0.3 keV in the rest frame) and broad Fe Kα line,
extending down to 3 keV. The underlying X-ray continuum could be fitted
with an absorbed power law (with Γ = 1.8 ± 0.2 and N <SUB>H</SUB> =
5.9<SUP>+0.6</SUP> <SUB>-0.7</SUB> × 10<SUP>22</SUP> cm<SUP>-2</SUP>)
plus a soft component. If due to relativistically smeared reflection by
an X-ray illuminated accretion disk, the spin of the supermassive black
hole (SMBH) is constrained to be 0.97<SUP>+0.03</SUP> <SUB>-0.13</SUB>
(errors at 90% confidence level for one interesting parameter), and the
accretion system is viewed at an inclination angle of 37° ± 4°. This
would be the first type 2 active galactic nucleus reported with strong
red Fe Kα wing detected which demands a fast rotating SMBH. The
unusually large EW would suggest that the light bending effect is
strong in this source. Alternatively, the spectra could be fitted by
a dual-absorber model (though with a global χ<SUP>2</SUP> higher by
~6 for 283 dof) with N <SUB>H1</SUB> = 7.0 ± 0.8 × 10<SUP>22</SUP>
cm<SUP>-2</SUP> covering 100% of the X-ray source, and N <SUB>H2</SUB>
= 21.7<SUP>+5.6</SUP> <SUB>-5.4</SUB> × 10<SUP>22</SUP> cm<SUP>-2</SUP>
covering 71%, which does not require an extra broad Fe Kα line.
---------------------------------------------------------
Title: On the X-Ray Baldwin Effect in Active Galactic Nuclei Observed
by the Chandra High-energy Grating
Authors: Shu, X. W.; Wang, J. X.; Yaqoob, T.; Jiang, P.; Zhou, Y. Y.
2012ApJ...744L..21S Altcode: 2011arXiv1112.1569S
Using Chandra high-energy grating (HEG) observations of 32 active
galactic nuclei (AGNs), we present a systematic study of the X-ray
Baldwin effect (XBE; i.e., the anti-correlation between the narrow
Fe Kα line equivalent width (EW) and X-ray continuum luminosity
for AGN samples) with the highest spectral resolution currently
available. We have previously reported an anti-correlation with
EWvpropL <SUP>-0.22</SUP> <SUB>2-10 keV</SUB> in an HEG sample, and
the correlation is much weaker after averaging multiple observations of
individual AGNs (EWvpropL <SUP>-0.13</SUP> <SUB>2-10 keV</SUB>). This
indicates that rapid variation in the X-ray continuum plays an important
role in producing the XBE, and such an effect should also be visible
in individual AGNs. In this Letter, by normalizing the line EWs and
continuum luminosities to the time-averaged values for each AGN in our
sample with multiple HEG observations, we find a strong anti-correlation
between EW and L<SUB>X</SUB> (EW/langEWrangvprop(L/langLrang)<SUP>-0.82
± 0.10</SUP>), consistent with the XBE expected in an individual
AGN if the narrow line flux remains constant while the continuum
varies. This is first observational evidence that the Fe Kα line
flux in a large sample of AGNs lacks a corresponding response to
the continuum variation, supporting the fact that the narrow Fe-K
line emission originates from a region far from the nucleus. We then
performed Monte Carlo simulations to address whether the global XBE can
be produced by X-ray continuum variation solely, and found that such
an interpretation of the XBE cannot be ruled out statistically. One
should thus be very cautious before drawing any scientific conclusion
based on an observed XBE.
---------------------------------------------------------
Title: The Latitude Distribution of Small-scale Magnetic Elements
in Solar Cycle 23
Authors: Jin, C. L.; Wang, J. X.
2012ApJ...745...39J Altcode:
With the unique data set from full-disk observations provided by
Michelson Doppler Imager on board the Solar and Heliospheric Observatory
in the interval embodying solar cycle 23, we have found that the
cyclic variations of numbers and total flux of these small-scale
magnetic elements covering fluxes of (2.9-32.0) × 10<SUP>18</SUP>
Mx and (4.27-38.01) × 10<SUP>19</SUP> Mx show anticorrelation
and correlation with sunspots, respectively. In this study, the
time-latitude distributions of these anticorrelated and correlated
elements are analyzed. The following results are disclosed: (1)
for the correlated elements, the cyclic variations of the total flux
in low-latitude and middle-latitude regions show a longer duration
of cyclic maximum phase than that of an active region (AR) in the
corresponding latitude region; the total flux of these elements shows
the accordant south-north asymmetry with that of AR; the time-latitude
distribution of their number displays a similar butterfly diagram
but with a latitude distribution that is twice as wide as that of
sunspots. (2) For the anticorrelated elements, the time-latitude
distribution of number shows a solar cycle variation different from
the sunspot butterfly diagram; in each latitude, the distribution
of anticorrelated elements always shows the anticorrelated variation
with that of sunspots; during solar cycle 23, the average speed of the
peak latitudinal migration for anticorrelated elements reaches 7.5 deg
year<SUP>-1</SUP>, almost three times that for sunspots. These results
seem to imply that the correlated elements are the debris of decayed
sunspots, and the anticorrelated elements have a different source but
are affected or modulated by sunspot magnetic field.
---------------------------------------------------------
Title: Statistical properties of superactive regions during solar
cycles 19-23
Authors: Chen, A. Q.; Wang, J. X.; Li, J. W.; Feynman, J.; Zhang, J.
2011A&A...534A..47C Altcode:
Context. Each solar activity cycle is characterized by a small number
of superactive regions (SARs) that produce the most violent of space
weather events with the greatest disastrous influence on our living
environment. <BR /> Aims: We aim to re-parameterize the SARs and
study the latitudinal and longitudinal distributions of SARs. <BR />
Methods: We select 45 SARs in solar cycles 21-23, according to the
following four parameters: 1) the maximum area of sunspot group, 2)
the soft X-ray flare index, 3) the 10.7 cm radio peak flux, and 4)
the variation in the total solar irradiance. Another 120 SARs given
by previous studies of solar cycles 19-23 are also included. The
latitudinal and longitudinal distributions of the 165 SARs in both the
Carrington frame and the dynamic reference frame during solar cycles
19-23 are studied statistically. <BR /> Results: Our results indicate
that these 45 SARs produced 44% of all the X class X-ray flares during
solar cycles 21-23, and that all the SARs are likely to produce a very
fast CME. The latitudinal distributions of SARs display the Maunder
butterfly diagrams and SARs occur preferentially in the maximum period
of each solar cycle. Northern hemisphere SARs dominated in solar cycles
19 and 20 and southern hemisphere SARs dominated in solar cycles 21 and
22. In solar cycle 23, however, SARs occurred about equally in each
hemisphere. There are two active longitudes in both the northern and
southern hemispheres, about 160°-200° apart. Applying the improved
dynamic reference frame to SARs, we find that SARs rotate faster than
the Carrington rate and there is no significant difference between
the two hemispheres. The synodic periods are 27.19 days and 27.25
days for the northern and southern hemispheres, respectively. The
longitudinal distribution of SARs is significantly non-axisymmetric
and about 75% SARs occurred near two active longitudes with half
widths of 45°. <P />Appendix A is available in electronic form at
<A href="http://www.aanda.org">http://www.aanda.org</A>
---------------------------------------------------------
Title: Chandra High-energy Grating Observations of the Fe Kα Line
Core in Type II Seyfert Galaxies: A Comparison with Type I Nuclei
Authors: Shu, X. W.; Yaqoob, T.; Wang, J. X.
2011ApJ...738..147S Altcode: 2011arXiv1107.0195S
We present a study of the core of the Fe Kα emission line at ~6.4
keV in a sample of type II Seyfert galaxies observed by the Chandra
high-energy grating. The sample consists of 29 observations of 10 unique
sources. We present measurements of the Fe Kα line parameters with
the highest spectral resolution currently available. In particular,
we derive the most robust intrinsic line widths for some of the
sources in the sample to date. We obtained a weighted mean full
width at half-maximum (FWHM) of 2000 ± 160 km s<SUP>-1</SUP> for
8 out of 10 sources (the remaining sources had insufficient signal
to noise). From a comparison with the optical emission-line widths
obtained from spectropolarimetric observations, we found that the
location of Fe Kα line-emitting material is a factor of ~0.7-11 times
the size of the optical broad-line region. Furthermore, compared to 13
type I active galactic nuclei (AGNs) for which the best Fe Kα line
FWHM constraints were obtained, we found no difference in the FWHM
distribution or the mean FWHM, and this conclusion is independent of
the central black hole mass. This result suggests that the bulk of the
Fe Kα line emission may originate from a universal region at the same
radius with respect to the gravitational radius, ~3 × 10<SUP>4</SUP>
r<SUB>g</SUB> on average. By examining the correlation between the Fe
Kα luminosity and the [O IV] line luminosity, we found a marginal
difference in the Fe Kα line flux between type I and type II AGNs,
but the spread in the ratio of L <SUB>Fe</SUB> to L <SUB>[O IV]</SUB>
is about two orders of magnitude. Our results confirm the theoretical
expectation that the Fe Kα emission-line luminosity cannot trivially
be used as a proxy of the intrinsic AGN luminosity, unless a detailed
comparison of the data with proper models is applied.
---------------------------------------------------------
Title: The Sun's Small-scale Magnetic Elements in Solar Cycle 23
Authors: Jin, C. L.; Wang, J. X.; Song, Q.; Zhao, H.
2011ApJ...731...37J Altcode: 2011arXiv1102.3728J
With the unique database from the Michelson Doppler Imager on board
the Solar and Heliospheric Observatory in an interval embodying solar
cycle 23, the cyclic behavior of solar small-scale magnetic elements
is studied. More than 13 million small-scale magnetic elements are
selected, and the following results are found. (1) The quiet regions
dominated the Sun's magnetic flux for about 8 years in the 12.25 year
duration of cycle 23. They contributed (0.94-1.44) ×10<SUP>23</SUP>
Mx flux to the Sun from the solar minimum to maximum. The monthly
average magnetic flux of the quiet regions is 1.12 times that of
the active regions in the cycle. (2) The ratio of quiet region flux
to that of the total Sun equally characterizes the course of a solar
cycle. The 6 month running average flux ratio of the quiet regions was
larger than 90.0% for 28 continuous months from July 2007 to October
2009, which very well characterizes the grand solar minima of cycles
23-24. (3) From the small to the large end of the flux spectrum, the
variations of numbers and total flux of the network elements show
no correlation, anti-correlation, and correlation with sunspots,
respectively. The anti-correlated elements, covering the flux of
(2.9-32.0)×10<SUP>18</SUP> Mx, occupy 77.2% of the total element
number and 37.4% of the quiet-Sun flux. These results provide insight
into the reason for anti-correlations of small-scale magnetic activity
during the solar cycle.
---------------------------------------------------------
Title: Small-scale magnetic elements in Solar Cycle 23
Authors: Jin, C. L.; Wang, J. X.; Song, Q.; Zhao, H.
2011arXiv1102.3485J Altcode:
With the unique database from Michelson Doppler Imager aboard the
Solar and Heliospheric Observatory in an interval embodying solar
cycle 23, the cyclic behavior of solar small-scale magnetic elements
is studied. More than 13 million small-scale magnetic elements are
selected, and the following results are unclosed. (1) The quiet regions
dominated the Sun\textsf{'}s magnetic flux for about 8 years in the
12.25 year duration of Cycle 23. They contributed (0.94 -- 1.44) $\times
10^{23}$ Mx flux to the Sun from the solar minimum to maximum. The
monthly average magnetic flux of the quiet regions is 1.12 times that of
active regions in the cycle. (2) The ratio of quiet region flux to that
of the total Sun equally characterizes the course of a solar cycle. The
6-month running-average flux ratio of quiet region had been larger than
90.0% for 28 continuous months from July 2007 to October 2009, which
characterizes very well the grand solar minima of Cycles 23-24. (3)
From the small to large end of the flux spectrum, the variations of
numbers and total flux of the network elements show no-correlation,
anti-correlation, and correlation with sunspots, respectively. The
anti-correlated elements, covering the flux of (2.9 - 32.0)$\times
10^{18}$ Mx, occupies 77.2% of total element number and 37.4% of quiet
Sun flux. These results provide insight into reason for anti-correlated
variations of small-scale magnetic activity during the solar cycle.
---------------------------------------------------------
Title: A current sheet traced from the Sun to interplanetary space
Authors: Zhou, G. P.; Xiao, C. J.; Wang, J. X.; Wheatland, M. S.;
Zhao, H.
2011A&A...525A.156Z Altcode:
Context. Magnetic reconnection is a central concept for understanding
solar activity, including filament eruptions, flares, and coronal mass
ejections (CMEs). The existence of transverse and vertical current
sheets, sites where reconnection takes place in the solar atmosphere,
is frequently proposed as a precondition for flare/CME models, but is
rarely identified in observations. <BR /> Aims: We aim at identifying
a transverse current sheet that existed in the pre-CME structure and
persisted from the CME solar source to interplanetary space. <BR />
Methods: STEREO A/B provide us a unique opportunity to calculate the
interplanetary current sheets for the magnetic cloud. We analyze
such a structure related to the fast halo CME of 2006 December 13
with assembled observations. A current sheet at the front of the
magnetic cloud is analyzed to its origin in a transverse current
sheet in the CME solar source, which can be revealed in the magnetic
field extrapolations, XRT, and LASCO observations. <BR /> Results:
An interplanetary current sheet is identified as coming from the CME
solar source by carefully mapping and examining multiple observations
from the Sun to interplanetary space, along with nonlinear force-free
magnetic field extrapolations of the active region NOAA 10930. <BR />
Conclusions: The structure identified in the pre-flare state is a global
transverse current sheet, which plays a role in the CME initiation,
and propagates from the corona to interplanetary space.
---------------------------------------------------------
Title: Solar cycle variation of network magnetic elements
Authors: Wang, J. X.; Jin, C. L.
2011ASInC...2..163W Altcode:
With the unique database from Michelson Doppler Imager aboard the
Solar and Heliospheric Observatory in an interval embodying solar
cycle 23, the cyclic behavior of solar small-scale magnetic elements
is studied. More than 13 million solar network magnetic elements are
selected, and the following results are discussed. (1) With increasing
flux per element, the number variation of the network elements shows a
three-fold scenario: no-correlation, anti-correlation, and correlation
with sunspots, respectively. The anti-correlated elements cover
flux range of (2.9 - 32.0)× 10^{18} Mx, and occupy 77.2% of total
network elements. (2) The latitude distribution of the correlated
elements follows the sunspot butterfly diagram in the solar cycle
but has wider latitude distribution than sunspots. Furthermore, the
anti-correlated elements also show much broad latitude distribution,
but a moderate migration toward equator during the solar maximum which
was clearly out of phase with sunspots. These results shed new light
in understanding anti-correlated variations of small-scale solar
activity, e.g., X-ray coronal bright points, and the origin of the
Sun's small-scale magnetism.
---------------------------------------------------------
Title: Erratum to: Solar Intranetwork Magnetic Elements: Evolution
and Lifetime
Authors: Zhou, G. P.; Wang, J. X.; Jin, C. L.
2010SoPh..267..493Z Altcode: 2010SoPh..tmp..221Z; 2010SoPh..tmp..197Z
No abstract at ADS
---------------------------------------------------------
Title: Solar Intranetwork Magnetic Elements: Evolution and Lifetime
Authors: Zhou, G. P.; Wang, J. X.; Jin, C. L.
2010SoPh..267...63Z Altcode: 2010SoPh..tmp..173Z
Based on Hinode SOT/NFI observations with greatly improved spatial
and temporal resolution and polarization sensitivity, the lifestory
of the intranetwork (IN) magnetic elements are explored in a solar
quiet region. A total of 2282 IN elements are followed from their
appearance to disappearance and their fluxes measured. By tracing
individual IN elements their lifetimes are obtained, which fall in
the range from 1 to 20 min. The average lifetime is 2.9±2.0 min. The
observed lifetime distribution is well represented by an exponential
function. Therefore, the e-fold characteristic lifetime is determined by
a least-square fitting to the observations, which is 2.1±0.3 min. The
lifetime of IN elements is correlated closely with their flux. The
evolution of IN elements is described according to the forms of their
birth and disappearance. Based on the lifetime and flux obtained from
the new observations, it is estimated that the IN elements have the
capacity of heating the corona with a power of 2.1×10<SUP>28</SUP>
erg s<SUP>−1</SUP> for the whole Sun.
---------------------------------------------------------
Title: XMM-Newton Observations of the Seyfert 2 Galaxy NGC 7590:
The Nature of X-ray Absorption
Authors: Shu, X. W.; Liu, T.; Wang, J. X.
2010ApJ...722...96S Altcode: 2010arXiv1008.1502S
We present the analysis of three XMM-Newton observations of the Seyfert
2 galaxy NGC 7590. The source was found to have no X-ray absorption
in the low spatial resolution ASCA data. The XMM-Newton observations
provide a factor of ~10 better spatial resolution than previous ASCA
data. We find that the X-ray emission of NGC 7590 is dominated by an
off-nuclear ultra-luminous X-ray source and an extended emission from
the host galaxy. The nuclear X-ray emission is rather weak compared
with the host galaxy. Based on its very low X-ray luminosity as well
as the small ratio between the 2-10 keV and the [O III] fluxes, we
interpret NGC 7590 as Compton-thick rather than being an "unobscured"
Seyfert 2 galaxy. Future higher resolution observations such as Chandra
are crucial to shed light on the nature of the NGC 7590 nucleus.
---------------------------------------------------------
Title: X-ray Properties of the z ~ 4.5 Lyα Emitters in the Chandra
Deep Field South Region
Authors: Zheng, Z. Y.; Wang, J. X.; Finkelstein, S. L.; Malhotra,
S.; Rhoads, J. E.; Finkelstein, K. D.
2010ApJ...718...52Z Altcode: 2010arXiv1005.3829Z
We report the first X-ray detection of Lyα emitters (LAEs) at
redshift z ~ 4.5. One source (J033127.2-274247) is detected in the
Extended Chandra Deep Field-South (ECDF-S) X-ray data and has been
spectroscopically confirmed as a z = 4.48 quasar with L<SUB>X</SUB> =
4.2 × 10<SUP>44</SUP> erg s<SUP>-1</SUP>. The single detection gives
an Lyα quasar density of ~ 2.7<SUP>+6.2</SUP> <SUB>-2.2</SUB> ×
10<SUP>-6</SUP> Mpc<SUP>-3</SUP>, consistent with the X-ray luminosity
function of quasars. Another 22 LAEs in the central Chandra Deep
Field-South region are not detected individually, but their co-added
counts yield an S/N = 2.4 (p = 99.83%) detection at soft band, with an
effective exposure time of ~36 Ms. Further analysis of the equivalent
width (EW) distribution shows that all the signals come from 12 LAE
candidates with EW<SUB>rest</SUB>< 400 Å and 2 of them contribute
about half of the signal. From follow-up spectroscopic observations,
we find that one of the two is a low-redshift emission-line galaxy,
and the other is a Lyman break galaxy at z = 4.4 with little or no Lyα
emission. Excluding these two and combined with ECDF-S data, we derive a
3σ upper limit on the average X-ray flux of F <SUB>0.5-2.0 keV</SUB>
< 1.6 × 10<SUP>-18</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP>,
which corresponds to an average luminosity of langL <SUB>0.5-2
keV</SUB>rang <2.4 × 10<SUP>42</SUP> erg s<SUP>-1</SUP> for z ~
4.5 LAEs. If the average X-ray emission is due to star formation,
it corresponds to a star formation rate (SFR) of <180-530 M
<SUB>sun</SUB> yr<SUP>-1</SUP>. We use this SFR<SUB> X </SUB> as an
upper limit of the unobscured SFR to constrain the escape fraction
of Lyα photons and find a lower limit of f <SUB>esc,Lyα</SUB> >
3%-10%. However, our upper limit on the SFR<SUB> X </SUB> is ~7 times
larger than the upper limit on SFR<SUB> X </SUB> on z ~ 3.1 LAEs in
the same field and at least 30 times higher than the SFR estimated from
Lyα emission. From the average X-ray-to-Lyα line ratio, we estimate
that fewer than 3.2% (6.3%) of our LAEs could be high-redshift type 1
(type 2) active galactic nuclei (AGNs) and those hidden AGNs likely
show low rest-frame EWs.
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Title: The Cores of the Fe Kα Lines in Active Galactic Nuclei:
An Extended Chandra High Energy Grating Sample
Authors: Shu, X. W.; Yaqoob, T.; Wang, J. X.
2010ApJS..187..581S Altcode: 2010arXiv1003.1790S
We extend the study of the core of the Fe Kα emission line at ~6.4
keV in Seyfert galaxies reported by Yaqoob & Padmanabhan using a
larger sample observed by the Chandra high-energy grating (HEG). The
sample consists of 82 observations of 36 unique sources with z <
0.3. Whilst heavily obscured active galactic nuclei are excluded
from the sample, these data offer some of the highest precision
measurements of the peak energy of the Fe Kα line, and the highest
spectral resolution measurements of the width of the core of the line in
unobscured and moderately obscured (N <SUB>H</SUB> < 10<SUP>23</SUP>
cm<SUP>-2</SUP>) Seyfert galaxies to date. From an empirical and uniform
analysis, we present measurements of the Fe Kα line centroid energy,
flux, equivalent width (EW), and intrinsic width (FWHM). The Fe Kα line
is detected in 33 sources, and its centroid energy is constrained in
32 sources. In 27 sources, the statistical quality of the data is good
enough to yield measurements of the FWHM. We find that the distribution
in the line centroid energy is strongly peaked around the value for
neutral Fe, with over 80% of the observations giving values in the
range 6.38-6.43 keV. Including statistical errors, 30 out of 32 sources
(~94%) have a line centroid energy in the range 6.35-6.47 keV. The mean
EW, among the observations in which a non-zero lower limit could be
measured, was 53 ± 3 eV. The mean FWHM from the subsample of 27 sources
was 2060 ± 230 km s<SUP>-1</SUP>. The mean EW and FWHM are somewhat
higher when multiple observations for a given source are averaged. From
a comparison with the Hβ optical emission-line widths (or, for one
source, Brα), we find that there is no universal location of the Fe
Kα line-emitting region relative to the optical broad-line region
(BLR). In general, a given source may have contributions to the Fe Kα
line flux from parsec-scale distances from the putative black hole, down
to matter a factor ~2 closer to the black hole than the BLR. We confirm
the presence of the X-ray Baldwin effect, an anti-correlation between
the Fe Kα line EW and X-ray continuum luminosity. The HEG data have
enabled isolation of this effect to the narrow core of the Fe Kα line.
---------------------------------------------------------
Title: NGC 2992 in an X-ray High State Observed by XMM-Newton:
Response of the Relativistic Fe Kα Line to the Continuum
Authors: Shu, X. W.; Yaqoob, T.; Murphy, K. D.; Braito, V.; Wang,
J. X.; Zheng, W.
2010ApJ...713.1256S Altcode: 2010arXiv1003.1789S
We present the analysis of an XMM-Newton observation of the Seyfert
galaxy NGC 2992. The source was found in its highest level of X-ray
activity yet detected, a factor ~23.5 higher in the 2-10 keV flux
than the historical minimum. NGC 2992 is known to exhibit X-ray
flaring activity on timescales of days to weeks, and the XMM-Newton
data provide at least a factor of ~3 better spectral resolution in
the Fe K band than any previously measured flaring X-ray state. We
find that there is a broad feature in the ~5-7 keV band that could be
interpreted as a relativistic Fe Kα emission line. Its flux appears
to have increased in tandem with the 2-10 keV continuum when compared
to a previous Suzaku observation when the continuum was a factor of
~8 lower than that during the XMM-Newton observation. The XMM-Newton
data are consistent with the general picture that increased X-ray
activity and corresponding changes in the Fe Kα line emission occur
in the innermost regions of the putative accretion disk. This behavior
contrasts with the behavior of other active galactic nuclei in which
the Fe Kα line does not respond to variability in the X-ray.
---------------------------------------------------------
Title: Is there more global solar activity on the Sun?
Authors: Wang, J. X.; Zhang, Y. Z.; Zhou, G. P.; Wen, Y. Y.; Jiang, J.
2010IAUS..264..251W Altcode:
There appear indications of more global activity on the Sun
which is larger, much beyond the scale of solar active regions
(ARs). These indications include formation, flaring and eruption of the
trans-equatorial loops seen in EUV and X-rays, formation and eruption of
trans-equatorial filaments, global magnetic connectivity in EUV dimming
associated with halo-coronal mass ejections, wide spread of radio burst
sources in meter wavelength in the solar corona, and quasi-simultaneous
magnetic flux emergence in both hemispheres seen during some major solar
events. With examples of a few major events in the last solar cycle we
discuss the possibility that there is large or global-scale activity
on the Sun. Its spatial scale is many times larger than that of AR
and temporal scale is over 10 hours. The exemplified trans-equatorial
loops are anchored in ARs and their activity is temporally associated
with flares in ARs too. In some sense the flares in ARs appear either
as a part of or a precursor of the more global activity. It is likely
that the combination of the flares in ARs and the associated global
activity is responsible to the major solar-terrestrial events. More
efforts in understanding the global activity are undertaken.
---------------------------------------------------------
Title: The Research on the Fast Static Precise Point Position Based
on Ridged Estimation
Authors: Li, H. J.; Wang, J. X.; Chen, J. P.; Hu, C. W.
2009AcASn..50..438L Altcode:
Precise Point Positioning (PPP) has been reported to have a precision at
centimeter level in static mode and at centimeter to decimeter level in
kinematic mode. However, the application of PPP to real-time is still
limited by its long convergence time, typically 30 minutes, which
is necessary for the float carrier phase ambiguity resolution. The
ambiguity free model of PPP can eliminate the initial phase
ambiguities through epoch-difference of phase observations. However,
this mode only estimates coordinate differences between two sequential
epochs. Therefore, the station coordinates need to be derived with
additional methods, e.g., combined with noised range observations. In
this paper, based on the phase epoch-difference, a fast static PPP
algorithm is developed, where parameters estimation is based on the
ridged estimation. The coordinates can be estimated by observations
only at two epochs, assuring the fast PPP. Using the 1 hour-data
collected on the 295th day of 2007 in Tongji University, a test was
carried out. Results show that the coordinate precision can be at
centimeter to decimeter level when the initial values are different.
---------------------------------------------------------
Title: Magnetic non-potentiality on the quiet Sun and the filigree
Authors: Zhao, Meng; Wang, Jing-Xiu; Jin, Chun-Lan; Zhou, Gui-Ping
2009RAA.....9..933Z Altcode:
From the observed vector magnetic fields by the Solar Optical
Telescope/Spectro-Polarimeter aboard the satellite Hinode, we have
examined whether or not the quiet Sun magnetic fields are non-potential,
and how the G-band filigrees and Ca II network bright points (NBPs)
are associated with the magnetic non-potentiality. A sizable
quiet region in the disk center is selected for this study. The
new findings by the study are as follows. (1) The magnetic fields
of the quiet region are obviously non-potential. The region-average
shear angle is 40<SUP>o</SUP>, the average vertical current is 0.016A
m<SUP>-2</SUP>, and the average free magnetic energy density, 2.7 ×
10<SUP>2</SUP> erg cm<SUP>-3</SUP>. The magnitude of these non-potential
quantities is comparable to that in solar active regions. (2) There
are overall correlations among current helicity, free magnetic
energy and longitudinal fields. The magnetic non-potentiality is
mostly concentrated in the close vicinity of network elements which
have stronger longitudinal fields. (3) The filigrees and NBPs are
magnetically characterized by strong longitudinal fields, large electric
helicity, and high free energy density. Because the selected region
is away from any enhanced network, these new results can generally
be applied to the quiet Sun. The findings imply that stronger network
elements play a role in high magnetic non-potentiality in heating the
solar atmosphere and in conducting the solar wind.
---------------------------------------------------------
Title: Flare-induced signals in polarization measurements during
the X2.6 flare on 2005 January 15
Authors: Zhao, Meng; Wang, Jing-Xiu; Matthews, Sarah; Ming-DeDing;
Zhao, Hui; Jin, Chun-Lan
2009RAA.....9..812Z Altcode:
Flare-induced signals in polarization measurements which were manifested
as apparent polarity reversal in magnetograms have been reported since
1981. We are motivated to further quantify the phenomenon by asking
two questions: can we distinguish the flare-induced signals from real
magnetic changes during flares, and what we can learn about flare
energy release from the flare-induced signals? We select the X2.6 flare
that occurred on 2005 January 15, for further study. The flare took
place in NOAA active region (AR) 10720 at approximately the central
meridian, which makes the interpretation of the vector magnetograms
less ambiguous. We have identified that flare-induced signals during
this flare appeared in six zones. The zones are located within an
average distance of 5 Mm from their weight center to the main magnetic
neutral line, have an average size of (0.6±0.4)×10<SUP>17</SUP>
cm<SUP>2</SUP>, duration of 13±4 min, and flux density change of
181±125 G in the area of reversed polarity. The following new facts
have been revealed by this study: (1) the flare-induced signal is
also seen in the transverse magnetograms but with smaller magnitude,
e.g., about 50 G; (2) the flare-induced signal mainly manifests itself
as apparent polarity reversal, but the signal starts and ends as a
weakening of flux density; (3) The flare-induced signals appear in
phase with the peaks of hard X-ray emission as observed by the Ramaty
High Energy Solar Spectroscopic Imager (RHESSI), and mostly trace the
position of RHESSI hard X-ray footpoint sources. (4) in four zones,
it takes place co-temporally with real magnetic changes which persist
after the flare. Only for the other two zones does the flux density
recover to the pre-flare level immediately after the flare. The physical
implications of the flare-induced signal are discussed in view of its
relevance to the non-thermal electron precipitation and primary energy
release in the flare.
---------------------------------------------------------
Title: Magnetic interactions during sympathetic solar eruptions
Authors: Jiang, Yun-Chun; Bi, Yi; Yang, Jia-Yan; Zheng, Rui-Sheng;
Wang, Jing-Xiu
2009RAA.....9..603J Altcode:
We present the first evidence for occurrences of magnetic interactions
between a jet, a filament and coronal loops during a complex event,
in which two flares sequentially occurred at different positions of
the same active region and were closely associated with two successive
coronal mass ejections (CMEs), respectively. The coronal loops were
located outside but nearby the filament channel before the flares. The
jet, originating from the first flare during its rise phase, not only
hit the filament body but also met one of the ends of the loops. The
filament then underwent an inclined eruption followed by the second
flare and met the same loop end once more. Both the jet and the filament
eruption were accompanied by the development of loop disturbances and
the appearances of brightenings around the meeting site. In particular,
the erupting filament showed clear manifestations of interactions with
the loops. After a short holdup, only its portion passed through this
site, while the other portion remained at the same place. Following
the filament eruption and the loop disappearance, four dimmings were
formed and located near their four ends. This is a situation that we
define as “quadrupolar dimmings." It appears that the two flares
consisted of a sympathetic pair physically linked by the interaction
between the jet and the filament, and their sympathy indicated that
of the two CMEs. Moreover, it is very likely that the two sympathetic
CMEs were simultaneously associated with the disappearing loops and
the quadrupole dimmings.
---------------------------------------------------------
Title: On VI Emission in Nuclear Region of NGC 1068
Authors: Zheng, W.; Kriss, G. A.; Wang, J. -X.; Sahnow, D.; Allen,
M.; Dopita, M.; Tsvetanov, Z.; Bicknell, G.
2009AIPC.1135...52Z Altcode:
FUSE Spectra of the nuclear region of NGC 1068 find strong OVI
emission consisting of a pair of narrow and broad components. There
is a gradient in the velocity field for the narrow O VI component
of ~200 kms<SUP>-1</SUP> from ~2” southwest of the nucleus to ~4”
northeast. A similar pattern is also observed with the broad O VI
component, with a gradient of ~3000 kms<SUP>-1</SUP>. These results
are consistent with the HST/STIS findings and suggest a biconical
structure in which the velocity field is mainly radial outflow.
---------------------------------------------------------
Title: The application of the LAMBDA method in the estimation of
the GPS slant wet vapour
Authors: Huang, S. Q.; Wang, J. X.; Wang, X. Y.; Chen, J. P.
2009AcASn..50...60H Altcode:
By far, the technology of GPS data processing has been improved well
and the accuracy of this processing has increased greatly. So, GPS has
been applied in meteorology widely.The SWV (Slant Wet Vapour) is a very
important parameter in the GPS meteorology. In 2004, Song Shuli had
advanced a SWV estimation method which used the precision orbit of JPL,
IGS clock and the LC observations without cycle-slip. But this method
is bad in real-time character. LAMBDA method, which is working well in
the VRS (Virtual Reference Station) /COORS, is used in the ambiguity
estimation. The method was proved by some true data calculation. The
ZTD(Zenith Time Delay), which is calculated by projecting SWD (Slant
Wet Delay) to zenith direction, has good coherence. Compairing the
ZTD with the results of GAMIT and BERNESE, the deviation between our
result and the GAMIT one is commonly little than 3cm, and the BERNESE
one is commonly little than 1.5cm.
---------------------------------------------------------
Title: Commission 10: Solar Activity
Authors: Klimchuk, James A.; van Driel-Gesztelyi, Lidia; Schrijver,
Carolus J.; Melrose, Donald B.; Fletcher, Lyndsay; Gopalswamy,
Natchimuthuk; Harrison, Richard A.; Mandrini, Cristina H.; Peter,
Hardi; Tsuneta, Saku; Vršnak, Bojan; Wang, Jing-Xiu
2009IAUTA..27...79K Altcode: 2008arXiv0809.1444K
Commission 10 deals with solar activity in all of its forms,
ranging from the smallest nanoflares to the largest coronal mass
ejections. This report reviews scientific progress over the roughly
two-year period ending in the middle of 2008. This has been an exciting
time in solar physics, highlighted by the launches of the Hinode and
STEREO missions late in 2006. The report is reasonably comprehensive,
though it is far from exhaustive. Limited space prevents the inclusion
of many significant results. The report is divided into the following
sections: Photosphere and chromosphere; Transition region; Corona and
coronal heating; Coronal jets; flares; Coronal mass ejection initiation;
Global coronal waves and shocks; Coronal dimming; The link between low
coronal CME signatures and magnetic clouds; Coronal mass ejections in
the heliosphere; and Coronal mass ejections and space weather. Primary
authorship is indicated at the beginning of each section.
---------------------------------------------------------
Title: Relativistic Outflows in Two Quasars in the Chandra Deep
Field South
Authors: Zheng, Z. Y.; Wang, J. X.
2008ApJ...688..116Z Altcode: 2008arXiv0807.4669Z
In this paper we provide new 1 Ms Chandra ACIS spectra of two quasars
in the Chandra Deep Field South (CDF-S) which had strong and extremely
blueshifted X-ray emission/absorption line features in previous 1 Ms
spectra, with outflowing bulk velocity v ~ 0.65-0.84c. In the new 1 Ms
spectra, the relativistic blueshifted line feature is solidly confirmed
in CXO CDFS J033225.3-274219 (CDFS 46, z = 1.617), and marginally
visible in CXO CDFS J033260.0-274748 (CDFS 11, z = 2.579), probably due
to the increased Chandra ACIS background in the new 1 Ms exposure. The
new data rule out the possibility (although very tiny already based
on the old 1Ms data) that the two sources were selected to be unusual
due to noise spikes in the spectra. The only likely interpretation is
extremely blueshifted iron absorption/emission lines or an absorption
edge due to relativistic outflow. We find that the rest-frame emission
line center in CDFS 46 marginally decreased from 16.2 to 15.2 keV after
7 years. The line shift could be due to either a decreasing outflowing
velocity or a lower ionization level. Including the two quasars reported
in this paper, we collect a total of 7 quasars from the literature
showing blueshifted emission or absorption line features with v >=
0.4c in X-ray spectra, and discuss their connection to jet and/or BAL
(broad absorption line) outflows.
---------------------------------------------------------
Title: A magnetic null geometry reconstructed from Cluster spacecraft
observations
Authors: He, J. -S.; Tu, C. -Y.; Tian, H.; Xiao, C. -J.; Wang, X. -G.;
Pu, Z. -Y.; Ma, Z. -W.; Dunlop, M. W.; Zhao, H.; Zhou, G. -P.; Wang,
J. -X.; Fu, S. -Y.; Liu, Z. -X.; Zong, Q. -G.; Glassmeier, K. -H.;
Reme, H.; Dandouras, I.; Escoubet, C. P.
2008JGRA..113.5205H Altcode:
This paper reports for the first time the identification of a magnetic
structure around a magnetic null in a magnetic reconnection region
in the magnetotail. Magnetic reconnection is one of the fundamental
processes in astrophysical and solar-terrestrial plasmas. Though
the concept of reconnection has been studied for many years,
the process that really occurs has not been fully revealed by
direct measurements. In particular, the lack of a description of
three-dimensional (3-D) reconnecting magnetic field from observations
makes the task more difficult. The Cluster spacecraft array provide an
opportunity to reconstruct the 3-D magnetic reconnection structure based
on magnetic field vectors simultaneously measured at four positions. The
identification of this structure comes from a new method of analysis
of in situ measurements proposed here. Applying a fitting model of 10
spherical harmonic functions and a Harris current sheet function, plus
a constant field, we reconstruct a 3-D magnetic field configuration
around the magnetic null in an reconnection event observed by Cluster
in the geo-magnetotail.
---------------------------------------------------------
Title: Determination of the Topology Skeleton of Magnetic Fields in
a Solar Active Region
Authors: Zhao, Hui; Wang, Jing-Xiu; Zhang, Jun; Xiao, Chi-Jie;
Wang, Hai-Min
2008ChJAA...8..133Z Altcode: 2007arXiv0712.3319Z
Magnetic topology has been a key to the understanding of magnetic
energy release mechanism. Based on observed vector magnetograms, we
have determined the three-dimensional (3D) topology skeleton of the
magnetic fields in the active region NOAA 10720. The skeleton consists
of six 3D magnetic nulls and a network of corresponding spines, fans,
and null-null lines. For the first time, we have identified a spiral
magnetic null in Sun's corona. The magnetic lines of force twisted
around the spine of the null, forming a `magnetic wreath' with excess
of free magnetic energy and resembling observed brightening structures
at extra-ultraviolet (EUV) wavebands. We found clear evidence of
topology eruptions which are referred to as catastrophic changes of
topology skeleton associated with a coronal mass ejection (CME) and an
explosive X-ray flare. These results shed new lights on the structural
complexity and its role in explosive magnetic activity. The concept of
flux rope has been widely used in modelling explosive magnetic activity,
although their observational identity is rather obscure or, at least,
lacking of necessary details up to date. We suggest that the magnetic
wreath associated with the 3D spiral null is likely an important class
of the physical entity of flux ropes.
---------------------------------------------------------
Title: Chandra X-Ray Sources in the LALA Cetus Field
Authors: Wang, J. X.; Zheng, Z. Y.; Malhotra, S.; Finkelstein, S. L.;
Rhoads, J. E.; Norman, C. A.; Heckman, T. M.
2007ApJ...669..765W Altcode: 2007arXiv0707.3239W
The 174 ks Chandra Advanced CCD Imaging Spectrometer exposure of
the Large Area Lyman Alpha Survey (LALA) Cetus field is the second
of the two deep Chandra images on LALA fields. In this paper we
present the Chandra X-ray sources detected in the Cetus field, along
with an analysis of X-ray source counts, stacked X-ray spectrum, and
optical identifications. A total of 188 X-ray sources were detected:
174 in the 0.5-7.0 keV band, 154 in the 0.5-2.0 keV band, and 113
in the 2.0-7.0 keV band. The X-ray source counts were derived and
compared with LALA field (172 ks exposure). Interestingly, we find
consistent hard-band X-ray source density, but (36+/-12)% higher
soft-band X-ray source density in Cetus field. The weighted stacked
spectrum of the detected X-ray sources can be fitted by a power law
with photon index Γ=1.55. Based on the weighted stacked spectrum,
we find that the resolved fraction of the X-ray background drops from
(72+/-1)% at 0.5-1.0 keV to (63+/-4)% at 6.0-8.0 keV. The unresolved
spectrum can be fitted by a power law over the range 0.5-7 keV, with a
photon index Γ=1.22. We also present optical counterparts for 154 of
the X-ray sources, down to a limiting magnitude of r<SUP>'</SUP>=25.9
(Vega), using a deep r'-band image obtained with the MMT. <P />Optical
Observations reported here were obtained at the MMT Observatory, a joint
facility of the University of Arizona and the Smithsonian Institution.
---------------------------------------------------------
Title: Nuclear Obscuration in Seyfert 2 Galaxies with and without
Polarized Broad Emission Lines
Authors: Shu, X. W.; Wang, J. -X.; Jang, P.; Fan, L. L.; Wang, T. -G.
2007ASPC..373..507S Altcode:
We compiled a sample of 54 Seyfert 2 galaxies with both
spectropolarimetric and X-ray observations to investigate the role
of nuclear obscuration in the visibility of polarized broad emission
lines (PBL). We find that at L<SUB>[O III]</SUB> > 10<SUP>41</SUP>
ergs s<SUP>-1</SUP>, Seyfert 2 galaxies without PBL are more obscured
in X-ray (at a confidence level of 99%). Our results explain the
non-detections of PBL under the framework of the unified model, and
put strong constraint on the geometry of the obscuring torus and the
scattering region.
---------------------------------------------------------
Title: On the X-ray Baldwin Effect for the Narrow Fe Kα Emission Line
Authors: Jiang, P.; Wang, J. -X.; Wang, T. -G.
2007ASPC..373..143J Altcode:
We build a large AGN sample with narrow FeK line measurements by
combining the archival Chandra HETG observations of 34 type 1 AGNs with
XMM-Newton observations in literature. We find a similar X-ray Baldwin
effect as reported earlier by Page et al. in the sample; however,
we note that the anti-correlation is dominated by the radio-loud
AGN in the sample, whose X-ray spectra might be contaminated by the
relativistic jet. Excluding the radio-loud AGN, we find a much weaker
anti-correlation. We present Monte Carlo simulations showing that such
a weak anti-correlation can be attributed to the relative short time
scale variations of the X-ray continuum.
---------------------------------------------------------
Title: Polarization of Quasars: Rotated and Funnel-shaped Outflow
Authors: Wang, H. -Y.; Wang, T. -G.; Wang, J. -X.
2007ASPC..373..335W Altcode: 2006astro.ph.12339W
Polarization is a useful probe to investigate the geometries and
dynamics of outflows in BAL QSOs. We perform a Monte Carlo simulation to
calculate the polarization produced by resonant and electron scattering
in BALR. We find: 1) A rotated and funnel-shaped outflow is preferred
to explain many observed polarization features. 2) Resonant scattering
can contribute a significant part of the N V emission line in some QSOs.
---------------------------------------------------------
Title: Satellite observations of separator-line geometry of
three-dimensional magnetic reconnection
Authors: Xiao, C. J.; Wang, X. G.; Pu, Z. Y.; Ma, Z. W.; Zhao, H.;
Zhou, G. P.; Wang, J. X.; Kivelson, M. G.; Fu, S. Y.; Liu, Z. X.;
Zong, Q. G.; Dunlop, M. W.; Glassmeier, K. -H.; Lucek, E.; Reme, H.;
Dandouras, I.; Escoubet, C. P.
2007NatPh...3..609X Altcode: 2007arXiv0705.1021X
Detection of a separator line that connects magnetic nulls and
the determination of the dynamics and plasma environment of such a
structure can improve our understanding of the three-dimensional (3D)
magnetic reconnection process. However, this type of field and particle
configuration has not been directly observed in space plasmas. Here we
report the identification of a pair of nulls, the null-null line that
connects them, and associated fans and spines in the magnetotail of
the Earth using data from the four Cluster spacecraft. With di and de
designating the ion and electron inertial lengths, respectively, the
separation between the nulls is found to be ~0.7+/-0.3d<SUB>i</SUB>
and an associated oscillation is identified as a lower-hybrid wave
with wavelength ~d<SUB>e</SUB>. This in situ evidence of the full 3D
reconnection geometry and associated dynamics provides an important
step towards establishing an observational framework of 3D reconnection.
---------------------------------------------------------
Title: A Catastrophic Flux Rope in a Quadrupole Magnetic Field for
Coronal Mass Ejections
Authors: Zhang, Y. -Z.; Wang, J. -X.
2007ApJ...663..592Z Altcode:
We propose a flux-rope model for the initiation of flare-associated
CMEs. The model triggers the eruption with a catastrophic loss of MHD
equilibrium and then requires magnetic reconnection to sustain the
eruption's acceleration. We carry out 2.5-dimensional time-dependent
resistive MHD simulations, choosing the initial state such that a flux
rope embedded in a quadrupole field is attached to the solar surface;
we then increase the magnetic flux of the rope by two different amounts,
thus obtaining two cases. One exhibits a gradual acceleration of the
flux rope, whereas the other produces an immediate acceleration. In
both cases, the maximum speed of the flux rope is representative of
a fast CME. Thus, we conclude that the flux-rope dynamics depends on
the intensity of the emergent magnetic flux. Our model does reproduce
the three-component structure of CMEs.
---------------------------------------------------------
Title: A Study of the Periodicities of Solar Filament Activity
Authors: Song, Wen-bin; Wang, Jing-xiu
2007ChA&A..31..270S Altcode:
Using the filament catalogues of Meudon Observatory, France, we
have compiled a daily count sequence of filaments from July 1957
to December 2004 and carried out a periodicity analysis with the
Scargle periodogram and Morlet wavelet transform. It is discovered
that this sequence exhibits four evident periods: 1557, 1141, 795 and
367 days. The characteristics of the variations of these periods are
analyzed in detail and the phases, physical mechanisms as well as the
mutual relations of some of the periods are briefly discussed.
---------------------------------------------------------
Title: A dynamo model for axisymmetric and non-axisymmetric solar
magnetic fields
Authors: Jiang, J.; Wang, J. X.
2007MNRAS.377..711J Altcode: 2007astro.ph..2508J; 2007MNRAS.tmp..253J
More and more observations are showing a relatively weak, but
persistent, non-axisymmetric magnetic field co-existing with the
dominant axisymmetric field on the Sun. Its existence indicates that the
non-axisymmetric magnetic field plays an important role in the origin
of solar activity. A linear non-axisymmetric α<SUP>2</SUP>-Ω dynamo
model is derived to explore the characteristics of the axisymmetric
(m = 0) and the first non-axisymmetric (m = 1) modes and to provide
a theoretical basis with which to explain the `active longitude',
`flip-flop' and other non-axisymmetric phenomena. The model consists of
an updated solar internal differential rotation, a turbulent diffusivity
varying with depth, and an α-effect working at the tachocline in a
rotating spherical system. The difference between the α<SUP>2</SUP>-Ω
and the α-Ω models and the conditions that favour the non-axisymmetric
modes under solar-like parameters are also presented.
---------------------------------------------------------
Title: Determination of the ν<SUB>e</SUB> and total B8 solar neutrino
fluxes using the Sudbury Neutrino Observatory Phase I data set
Authors: Aharmim, B.; Ahmad, Q. R.; Ahmed, S. N.; Allen, R. C.;
Andersen, T. C.; Anglin, J. D.; Bühler, G.; Barton, J. C.; Beier,
E. W.; Bercovitch, M.; Bergevin, M.; Bigu, J.; Biller, S. D.; Black,
R. A.; Blevis, I.; Boardman, R. J.; Boger, J.; Bonvin, E.; Boulay,
M. G.; Bowler, M. G.; Bowles, T. J.; Brice, S. J.; Browne, M. C.;
Bullard, T. V.; Burritt, T. H.; Cameron, J.; Chan, Y. D.; Chen, H. H.;
Chen, M.; Chen, X.; Cleveland, B. T.; Cowan, J. H. M.; Cowen, D. F.;
Cox, G. A.; Currat, C. A.; Dai, X.; Dalnoki-Veress, F.; Davidson,
W. F.; Deng, H.; Dimarco, M.; Doe, P. J.; Doucas, G.; Dragowsky, M. R.;
Duba, C. A.; Duncan, F. A.; Dunford, M.; Dunmore, J. A.; Earle, E. D.;
Elliott, S. R.; Evans, H. C.; Ewan, G. T.; Farine, J.; Fergani, H.;
Ferraris, A. P.; Fleurot, F.; Ford, R. J.; Formaggio, J. A.; Fowler,
M. M.; Frame, K.; Frank, E. D.; Frati, W.; Gagnon, N.; Germani, J. V.;
Gil, S.; Goldschmidt, A.; Goon, J. T. M.; Graham, K.; Grant, D. R.;
Guillian, E.; Hahn, R. L.; Hallin, A. L.; Hallman, E. D.; Hamer,
A. S.; Hamian, A. A.; Handler, W. B.; Haq, R. U.; Hargrove, C. K.;
Harvey, P. J.; Hazama, R.; Heeger, K. M.; Heintzelman, W. J.; Heise,
J.; Helmer, R. L.; Henning, R.; Hepburn, J. D.; Heron, H.; Hewett,
J.; Hime, A.; Howard, C.; Howe, M. A.; Huang, M.; Hykaway, J. G.;
Isaac, M. C. P.; Jagam, P.; Jamieson, B.; Jelley, N. A.; Jillings,
C.; Jonkmans, G.; Kazkaz, K.; Keener, P. T.; Kirch, K.; Klein, J. R.;
Knox, A. B.; Komar, R. J.; Kormos, L. L.; Kos, M.; Kouzes, R.; Krüger,
A.; Kraus, C.; Krauss, C. B.; Kutter, T.; Kyba, C. C. M.; Labranche,
H.; Lange, R.; Law, J.; Lawson, I. T.; Lay, M.; Lee, H. W.; Lesko,
K. T.; Leslie, J. R.; Levine, I.; Loach, J. C.; Locke, W.; Luoma,
S.; Lyon, J.; MacLellan, R.; Majerus, S.; Mak, H. B.; Maneira, J.;
Marino, A. D.; Martin, R.; McCauley, N.; McDonald, A. B.; McDonald,
D. S.; McFarlane, K.; McGee, S.; McGregor, G.; Drees, R. Meijer; Mes,
H.; Mifflin, C.; Miknaitis, K. K. S.; Miller, M. L.; Milton, G.;
Moffat, B. A.; Monreal, B.; Moorhead, M.; Morrissette, B.; Nally,
C. W.; Neubauer, M. S.; Newcomer, F. M.; Ng, H. S.; Nickel, B. G.;
Noble, A. J.; Norman, E. B.; Novikov, V. M.; Oblath, N. S.; Okada,
C. E.; O'Keeffe, H. M.; Ollerhead, R. W.; Omori, M.; Orrell, J. L.;
Oser, S. M.; Ott, R.; Peeters, S. J. M.; Poon, A. W. P.; Prior, G.;
Reitzner, S. D.; Rielage, K.; Roberge, A.; Robertson, B. C.; Robertson,
R. G. H.; Rosendahl, S. S. E.; Rowley, J. K.; Rusu, V. L.; Saettler,
E.; Schülke, A.; Schwendener, M. H.; Secrest, J. A.; Seifert, H.;
Shatkay, M.; Simpson, J. J.; Sims, C. J.; Sinclair, D.; Skensved,
P.; Smith, A. R.; Smith, M. W. E.; Starinsky, N.; Steiger, T. D.;
Stokstad, R. G.; Stonehill, L. C.; Storey, R. S.; Sur, B.; Tafirout,
R.; Tagg, N.; Takeuchi, Y.; Tanner, N. W.; Taplin, R. K.; Thorman,
M.; Thornewell, P. M.; Tolich, N.; Trent, P. T.; Tserkovnyak, Y. I.;
Tsui, T.; Tunnell, C. D.; van Berg, R.; van de Water, R. G.; Virtue,
C. J.; Walker, T. J.; Wall, B. L.; Waltham, C. E.; Tseung, H. Wan
Chan; Wang, J. -X.; Wark, D. L.; Wendland, J.; West, N.; Wilhelmy,
J. B.; Wilkerson, J. F.; Wilson, J. R.; Wittich, P.; Wouters, J. M.;
Wright, A.; Yeh, M.; Zuber, K.
2007PhRvC..75d5502A Altcode: 2006nucl.ex..10020S
This article provides the complete description of results from the
Phase I data set of the Sudbury Neutrino Observatory (SNO). The
Phase I data set is based on a 0.65 kiloton-year exposure of
<SUP>2</SUP>H<SUB>2</SUB>O (in the following denoted as D<SUB>2</SUB>O)
to the solar B8 neutrino flux. Included here are details of the SNO
physics and detector model, evaluations of systematic uncertainties,
and estimates of backgrounds. Also discussed are SNO's approach to
statistical extraction of the signals from the three neutrino reactions
(charged current, neutral current, and elastic scattering) and the
results of a search for a day-night asymmetry in the ν<SUB>e</SUB>
flux. Under the assumption that the B8 spectrum is undistorted,
the measurements from this phase yield a solar ν<SUB>e</SUB> flux of
ϕ(ν<SUB>e</SUB>)=1.76<SUB>-0.05</SUB><SUP>+0.05</SUP>(stat.)<SUB>-0.09</SUB><SUP>+0.09</SUP>(syst.)×10<SUP>6</SUP>
cm<SUP>-2</SUP> s<SUP>-1</SUP> and a non-ν<SUB>e</SUB> component of
ϕ(ν<SUB>μτ</SUB>)=3.41<SUB>-0.45</SUB><SUP>+0.45</SUP>(stat.)<SUB>-0.45</SUB><SUP>+0.48</SUP>(syst.)×10<SUP>6</SUP>
cm<SUP>-2</SUP> s<SUP>-1</SUP>. The sum of these components provides a
total flux in excellent agreement with the predictions of standard solar
models. The day-night asymmetry in the ν<SUB>e</SUB> flux is found to
be A<SUB>e</SUB>=7.0±4.9(stat.)<SUB>-1.2</SUB><SUP>+1.3</SUP>%(syst.),
when the asymmetry in the total flux is constrained to be zero.
---------------------------------------------------------
Title: Magnetic Properties of Metric Noise Storms Associated with
Coronal Mass Ejections
Authors: Wen, Ya-Yuan; Wang, Jing-Xiu; Zhang, Yu-Zong
2007ChJAA...7..265W Altcode:
Using Nançay Radioheliograph (NRH) imaging observations, combined
with SOHO/Michelson Doppler Imager (MDI) magnetogram observations and
coronal magnetic field extrapolation, we studied the magnetic nature
of metric noise storms that are associated with coronal mass ejections
(CMEs). Four events are selected: the events of 2000 July 14, 2001
April 26, 2002 August 16 and 2001 March 28. The identified noise storm
sources cover or partially cover the active regions (ARs), but the
centers of storm sources are offset from the ARs. Using extrapolated
magnetic field lines, we find that the noise storm sources trace the
boundary between the open and closed field lines. We demonstrate that
the disappearance of noise storm source is followed by the appearance of
the burst source. The burst sources spread on the solar disk and their
distributions correspond to the extent of the CME in LASCO C2 field of
view. All the SOHO/Extreme Ultraviolet Imaging Telescope (EIT) dimmings
associated with noise storm sources are located at the periphery of
noise storms where the magnetic lines of force were previously closed
and low-lying. When the closed field becomes partially or fully open,
the basic configurations of noise storm sources are changed, then
the noise storm sources are no longer observed. These observations
provide the information that the variations of noise storms manifest
the restructuring or reconfiguring of the coronal magnetic field.
---------------------------------------------------------
Title: Investigating the Nuclear Obscuration in Two Types of Seyfert
2 Galaxies
Authors: Shu, X. W.; Wang, J. X.; Jiang, P.; Fan, L. L.; Wang, T. G.
2007ApJ...657..167S Altcode: 2006astro.ph..3338S
We build a large sample of Seyfert 2 galaxies (Sy2s) with both
optical spectropolarimetric and X-ray data available, in which
29 of the Sy2s have a detection of polarized broad emission
lines (PBLs) and 25 do not. We find that for luminous Sy2s with
L<SUB>[OIII</SUB>>10<SUP>41</SUP> ergs s<SUP>-1</SUP>, sources with
PBLs have smaller X-ray absorption column densities in comparison to
those without PBLs (at a 92.3% confidence level): most of the Sy2s
with N<SUB>H</SUB><10<SUP>23.8</SUP> cm<SUP>-2</SUP> show PBLs
(86%; 12 out of 14), while the fraction is much smaller for sources
with heavier obscuration (54%; 15 out of 28). The confidence level
of the difference in absorption bounces up to 99.1% when using the
thickness (“T”) ratio (F<SUB>2-10keV</SUB>/F<SUB>[OIII</SUB>) as an
indicator. We rule out observation or selection bias as the origin for
the difference. Our results, for the first time with high statistical
confidence, show that, in additional to the activity of the nuclei,
the nuclear obscuration also plays an important role in the visibility
of PBLs in Sy2s. These results can be interpreted in the framework of
the unified model. We can reach these results in the unified model if
(1) the absorption column density is higher at large inclinations and
(2) the scattering region is obscured at large inclinations.
---------------------------------------------------------
Title: Most Hard-X-Ray-Selected Quasars in the Chandra Deep Fields
are Obscured
Authors: Wang, J. X.; Jiang, P.; Zheng, Z. Y.; Tozzi, P.; Norman,
C.; Giacconi, R.; Gilli, R.; Hasinger, G.; Kewley, L.; Mainieri,
V.; Nonino, M.; Rosati, P.; Streblyanska, A.; Szokoly, G.; Zirm, A.;
Zheng, W.
2007ApJ...657...95W Altcode: 2006astro.ph.11251W
Measuring the population of obscured quasars is one of the key issues
in understanding the evolution of active galactic nuclei (AGNs). With
a redshift completeness of 99%, the X-ray sources detected in the
Chandra Deep Field South (CDF-S) provide the best sample for this
issue. In this paper, we study the population of obscured quasars in
CDF-S by choosing the 4-7 keV selected sample, which is less biased
by the intrinsic X-ray absorption. The 4-7 keV band-selected samples
also filter out most of the X-ray-faint sources with too few counts,
for which the measurements of N<SUB>H</SUB> and L<SUB>X</SUB> have
very large uncertainties. Simply adopting the best-fit L<SUB>2-10
keV</SUB> and N<SUB>H</SUB>, we find that 71%+/-19% (20 out of 28)
of the quasars (with intrinsic L<SUB>2-10 keV</SUB>>10<SUP>44</SUP>
ergs s<SUP>-1</SUP>) are obscured with N<SUB>H</SUB>>10<SUP>22</SUP>
cm<SUP>-2</SUP>. Taking into account the uncertainties in the
measurements of both N<SUB>H</SUB> and L<SUB>X</SUB>, conservative lower
and upper limits for the fraction are 54% (13 out 24) and 84% (31 out
37). In the Chandra Deep Field North, the number is 29%; however, this
is mainly due to the redshift incompleteness. We estimate a fraction
of ~50%-63% after correcting for the redshift incompleteness with a
straightforward approach. Our results robustly confirm the existence
of a large population of obscured quasars.
---------------------------------------------------------
Title: Commission 10: Solar Activity
Authors: Melrose, Donald B.; Klimchuk, James A.; Benz, A. O.; Craig,
I. J. D.; Gopalswamy, N.; Harrison, R. A.; Kozlovsky, B. Z.; Poletto,
G.; Schrijver, K. J.; van Driel-Gesztelyi, L.; Wang, J. -X.
2007IAUTA..26...75M Altcode:
Commission 10 aims at the study of various forms of solar activity,
including networks, plages, pores, spots, fibrils, surges, jets,
filaments/prominences, coronal loops, flares, coronal mass ejections
(CMEs), solar cycle, microflares, nanoflares, coronal heating etc.,
which are all manifestation of the interplay of magnetic fields and
solar plasma. Increasingly important is the study of solar activities
as sources of various disturbances in the interplanetary space
and near-Earth "space weather".Over the past three years a major
component of research on the active Sun has involved data from the
RHESSI spacecraft. This review starts with an update on current and
planned solar observations from spacecraft. The discussion of solar
flares gives emphasis to new results from RHESSI, along with updates on
other aspects of flares. Recent progress on two theoretical concepts,
magnetic reconnection and magnetic helicity is then summarized, followed
by discussions of coronal loops and heating, the magnetic carpet
and filaments. The final topic discussed is coronal mass ejections
and space weather.The discussions on each topic is relatively brief,
and intended as an outline to put the extensive list of references
in context.The review was prepared jointly by the members of the
Organizing Committee, and the names of the primary contributors to
the various sections are indicated in parentheses.
---------------------------------------------------------
Title: Eruption of an Active-Region Filament Driven by an Emerging
Bipole
Authors: Jiang, Yun-Chun; Shen, Yuan-Deng; Wang, Jing-Xiu
2007ChJAA...7..129J Altcode:
A section of an S-shaped filament underwent an eruption in a
sigmoidal active region (AR 8027) with S-shaped coronal structure,
which was clearly driven by a bipole emerging below the NW end of
the filament. The bipole with two separating poles showed typical
characteristics of emerging flux region (EFR) and its axis rotated
counterclockwise. Two cancelling magnetic features (CMFs) were formed
between the two poles and adjacent flux with opposite polarity and
substantial flux cancellation occurred in them. Along with the bipole
emergence the filament was strongly disturbed. Just before the filament
eruption, two X-ray loops overlying the filament brightened, an axial
X-ray structure and then a cusp structure appeared. During the eruption
first the whole filament rose and then its SE end broke away from the
chromosphere, while its NW end remained stationary. Helical structure
and motion were observed in the filament body and downward mass motion
in the two ends. After the eruption, a major part of the filament
remained and slowly returned to quiescence, and an X-ray arcade and an
axial structure formed. These observations suggest that the eruption
resulted from the interaction between the bipole and the overlying
loops. We provide evidence that steady photospheric reconnection between
their footprints took place in the two CMFs during the bipole emergence.
---------------------------------------------------------
Title: VizieR Online Data Catalog: X-ray properties of AGN in CDFS
(Tozzi+, 2006)
Authors: Tozzi, P.; Gilli, R.; Mainieri, V.; Norman, C.; Risaliti,
G.; Rosati, P.; Bergeron, J.; Borgani, S.; Giacconi, R.; Hasinger,
G.; Nonino, M.; Streblyanska, A.; Szokoly, G.; Wang, J. X.; Zheng, W.
2007yCat..34510457T Altcode:
We present a detailed X-ray spectral analysis of the sources in the
1Ms catalog of the Chandra Deep Field South (CDFS, J/ApJS/139/369)
taking advantage of optical spectroscopy and photometric redshifts for
321 extragalactic sources out of the total sample of 347 sources. As
a default spectral model, we adopt a power law with slope Gamma with
an intrinsic redshifted absorption N<SUB>H</SUB>, a fixed Galactic
absorption and an unresolved Fe emission line. For 82 X-ray bright
sources, we are able to perform the X-ray spectral analysis leaving
both Gamma and N<SUB>H</SUB> free. <P />(1 data file).
---------------------------------------------------------
Title: Periodicities in solar filament activity
Authors: Song, W. B.; Wang, J. X.
2007AcASn..48...29S Altcode:
By using the Meudon filament catalogues we reconstruct a daily sequence
of filament counts from July 1957 to December 2004 and perform a
periodicity analysis with the methods of Scargle periodogram and Morlet
wavelet transform. As a result, four prominent periods are found around
1557, 1141, 795 and 367 days. We analyze their temporal variabilities
in detail and discuss some typical ones' phases, physical implications
and mutual relations briefly.
---------------------------------------------------------
Title: Two Successive Coronal Mass Ejections Driven by the Kink and
Drainage Instabilities of an Eruptive Prominence
Authors: Zhou, G. P.; Wang, J. X.; Zhang, J.; Chen, P. F.; Ji, H. S.;
Dere, K.
2006ApJ...651.1238Z Altcode:
We describe a clear case of the initiation of a propagating bright arc
and a CME on 2002 December 28, which were associated with an eruptive
prominence. In EIT 304 and 195 Å images, a very long filament showed
evidence of severe twisting in one of its fragments, which appeared as a
prominence on December 26; then, the prominence showed the conversion of
its twist into writhe. Two days later, the prominence displayed a slow
rising motion for hours. Internal twisting and mass motion took place
before the rapid acceleration and final eruption. The propagating bright
arc and the following CME corresponded to the early rising and the
subsequently eruptive phases of the prominence, respectively. Signatures
of magnetic reconnection, i.e., a cusp structure and postflare loops
in EUV wave bands and hard X-ray sources in the corona, were observed
after the prominence eruption. It appears that the kink instability
and the mass drainage in the prominence played key roles in triggering
the initiation of the CME. However, the rather impulsive acceleration
of the CME resulted from magnetic reconnection beneath the filament.
---------------------------------------------------------
Title: 3D Topology Structure of Coronal Magnetic Field
Authors: Zhao, H.; Wang, J. X.; Zhang, J.; Xiao, C. J.
2006IAUJD...3E..40Z Altcode:
We use the Poincaré index of isolated null-points in vector field
to strictly identify 3D null-points in coronal magnetic fields
reconstructed from the observed vector magnetogram of several important
active regions. Base on the null-points we identified, we reveal the
essential topology skeletons of 3D coronal magnetic fields. Comparing
these topology skeletons with images of H-alpha, EIT, TRACE and X-ray,
we find 3D topology structures of coronal magnetic fields are closely
associated with solar flares and CMEs. We also find indication of
3D magnetic reconnection by studying temporal series of 3D topology
structures of solar magnetic fields. To thoroughly investigate 3D
topology structures of coronal magnetic fields is a key to understand
the physical mechanism of solar activity.
---------------------------------------------------------
Title: On the Fraction of X-Ray-obscured Quasars in the Local Universe
Authors: Wang, J. X.; Jiang, P.
2006ApJ...646L.103W Altcode: 2006astro.ph..6333W
Recent wide-area hard X-ray and soft gamma-ray surveys have shown that
the fraction of X-ray-obscured active galactic nuclei (AGNs) in the
local universe significantly decreases with intrinsic luminosity. In
this Letter we point out that two corrections have to be made to
the samples: (1) radio-loud AGNs have to be excluded, since their
X-ray emission might be dominated by the jet component, and (2)
Compton-thick sources have to be excluded too, since their hard X-ray
and soft gamma-ray emission are also strongly attenuated by Compton
scattering. The soft gamma-ray-selected AGN samples obtained by Swift
and INTEGRAL provide the best opportunity to study the fraction of
obscured AGNs in the local universe in the least biased way. We choose
these samples to check if the corrections could alter the above result
on the fraction of obscured AGNs. We find that before the corrections
both samples show significant anticorrelation between L<SUB>X</SUB>
and N<SUB>H</SUB>, indicating an obvious decrease in the fraction of
obscured AGNs with luminosity. However, after the corrections, we find
only marginal evidence of anticorrelation (at the 98% confidence level)
in the Swift sample and no evidence at all in the INTEGRAL sample,
which consists of a comparable number of objects. We conclude that
current samples only show a marginal decrease in the fraction of
obscured AGNs in the local universe and that much larger samples are
required in order to reach a more robust conclusion.
---------------------------------------------------------
Title: Solar radiation pressure models for the GPS satellites
Authors: Chen, J. P.; Wang, J. X.
2006AcASn..47..310C Altcode:
The largest error in currently used for GPS orbit models is due to the
effect of solar radiation pressure (SRP). Over the last a few years
many improvement were made in modeling the orbits of GPS satellites
within the IGS. One of the most important factors for the improvement
is the perfect of SRP models. The main SRP models currently used for
GPS satellites is presented. Using different models, it can get the
performance of the models in satellite orbit determining. The results
show that new models developed by Bern University gain almost an order
of magnitude better than that of the other traditional models.
---------------------------------------------------------
Title: In situ evidence for the structure of the magnetic null in
a 3D reconnection event in the Earth's magnetotail
Authors: Xiao, C. J.; Wang, X. G.; Pu, Z. Y.; Zhao, H.; Wang, J. X.;
Ma, Z. W.; Fu, S. Y.; Kivelson, M. G.; Liu, Z. X.; Zong, Q. G.;
Glassmeier, K. H.; Balogh, A.; Korth, A.; Reme, H.; Escoubet, C. P.
2006NatPh...2..478X Altcode: 2006physics...6014X
Magnetic reconnection is one of the most important processes
in astrophysical, space and laboratory plasmas. Identifying the
structure around the point at which the magnetic field lines break and
subsequently reform, known as the magnetic null point, is crucial to
improving our understanding of reconnection. But owing to the inherently
three-dimensional nature of this process, magnetic nulls are only
detectable through measurements obtained simultaneously from at least
four points in space. Using data collected by the four spacecraft of
the Cluster constellation as they traversed a diffusion region in the
Earth's magnetotail on 15 September 2001, we report here the first
in situ evidence for the structure of an isolated magnetic null. The
results indicate that it has a positive-spiral structure whose spatial
extent is of the same order as the local ion inertial length scale,
suggesting that the Hall effect could play an important role in 3D
reconnection dynamics.
---------------------------------------------------------
Title: On the X-Ray Baldwin Effect for Narrow Fe Kα Emission Lines
Authors: Jiang, P.; Wang, J. X.; Wang, T. G.
2006ApJ...644..725J Altcode: 2006astro.ph..3339J
Most active galactic nuclei (AGNs) exhibit a narrow Fe Kα line at
~6.4 keV in the X-ray spectra, due to the fluorescent emission from
cold material far from the inner accretion disk. Using XMM-Newton
observations, Page et al. found that the equivalent width (EW)
of the narrow Fe Kα line decreases with increasing luminosity
(EW~L<SUP>-0.17+/-0.08</SUP>), suggesting a decrease in the
covering factor of the material emitting the line (presumably the
torus). By combining the archival Chandra HETG observations of 34
type 1 AGNs with XMM observations in the literature, we build a
much larger sample with 101 AGNs. We find a similar X-ray Baldwin
effect in the sample (EW~L<SUP>-0.2015+/-0.0426</SUP>) however,
we note that the anticorrelation is dominated by the radio-loud
AGNs in the sample, whose X-ray spectra might be contaminated by
the relativistic jet. Excluding the radio-loud AGNs, we find a much
weaker anticorrelation (EW~L<SUP>-0.1019+/-0.0524</SUP>). We present
Monte Carlo simulations showing that such a weak anticorrelation can
be attributed to the relative short timescale variations of the X-ray
continuum.
---------------------------------------------------------
Title: Catastrophic Behavior of Multiple Coronal Flux Rope System
Authors: Ding, J. Y.; Hu, Y. Q.; Wang, J. X.
2006SoPh..235..223D Altcode:
A major solar active event called Bastille Day Event occurred in AR
9077 on July 14, 2000. Simultaneous occurrence of a filament eruption,
a flare and a coronal mass ejection was observed in this event. Previous
analyses of this event show that before the event, there existed an
activation and eruption of a huge trans-equatorial filament, which
might play a crucial role in triggering the Bastille Day event. This
implies that independent flux systems are closely related to and affect
each other, which has encouraged us to investigate the catastrophic
behavior of a multiple coronal flux rope system with the use of a
2.5-D time-dependent MHD model. A force-free field that contains three
separate coronal flux ropes is taken to be the initial state. Starting
from this state, we increase either the annular or the axial flux of a
certain flux rope to examine the catastrophic behavior of the system in
two regimes, the ideal MHD regime and the resistive MHD regime. It is
found that a catastrophe occurs if the flux exceeds a certain critical
value, or the magnetic energy of the system exceeds a certain threshold:
the rope of interest breaks away from the base and escapes to infinity,
leaving a current sheet below. Moreover, the destiny of the remainder
flux ropes relies on whether reconnection takes place across the current
sheet. In the ideal MHD regime, i.e., in the absence of reconnection,
these ropes remain to be attached to the base in equilibrium, whereas in
the resistive MHD regime they abruptly erupt upward during reconnection
and escape to infinity. Reconnection causes the field lines to close
back to the base and thus changes the background field outside the
attached flux ropes in such a way that the constraint on these ropes
is substantially relaxed and the corresponding catastrophic energy
threshold is reduced accordingly, leading to a catastrophic eruption
of these ropes. Since magnetic reconnection is generally inevitable
when a current sheet forms and develops through an eruption of one
flux rope, the eruption of this flux rope must lead to an eruption of
the others. This provides an example to demonstrate the interaction
between several independent magnetic flux systems in different regions,
as implied by the Bastille Day event, and may serve as a possible
mechanism for sympathetic events occurring on the Sun.
---------------------------------------------------------
Title: X-ray spectral properties of active galactic nuclei in the
Chandra Deep Field South
Authors: Tozzi, P.; Gilli, R.; Mainieri, V.; Norman, C.; Risaliti,
G.; Rosati, P.; Bergeron, J.; Borgani, S.; Giacconi, R.; Hasinger,
G.; Nonino, M.; Streblyanska, A.; Szokoly, G.; Wang, J. X.; Zheng, W.
2006A&A...451..457T Altcode: 2006astro.ph..2127T
We present a detailed X-ray spectral analysis of the sources in the
1Ms catalog of the Chandra Deep Field South (CDFS) taking advantage of
optical spectroscopy and photometric redshifts for 321 extragalactic
sources out of the total sample of 347 sources. As a default spectral
model, we adopt a power law with slope Γ with an intrinsic redshifted
absorption N_H, a fixed Galactic absorption and an unresolved Fe
emission line. For 82 X-ray bright sources, we are able to perform the
X-ray spectral analysis leaving both Γ and N<SUB>H</SUB> free. The
weighted mean value for the slope of the power law is < Γ >
≃ 1.75 ± 0.02, and the distribution of best fit values shows an
intrinsic dispersion of σ_int ≃ 0.30. We do not find hints of a
correlation between the spectral index Γ and the intrinsic absorption
column density N_H. We then investigate the absorption distribution for
the whole sample, deriving the N<SUB>H</SUB> values in faint sources by
fixing Γ = 1.8. We also allow for the presence of a scattered component
at soft energies with the same slope of the main power law, and for a
pure reflection spectrum typical of Compton-thick AGN. We detect the
presence of a scattered soft component in 8 sources; we also identify
14 sources showing a reflection-dominated spectrum. The latter are
referred to as Compton-thick AGN candidates. By correcting for both
incompleteness and sampling-volume effects, we recover the intrinsic
N<SUB>H</SUB> distribution representative of the whole AGN population,
f(N_H) dN_H, from the observed one. f(N_H) shows a lognormal shape,
peaking around log(N_H)≃ 23.1 and with σ ≃ 1.1. Interestingly, such
a distribution shows continuity between the population of Compton-thin
and that of Compton-thick AGN. We find that the fraction of absorbed
sources (with N_H>10<SUP>22</SUP> cm<SUP>-2</SUP>) in the sample
is constant (at the level of about 75%) or moderately increasing with
redshift. Finally, we compare the optical classification to the X-ray
spectral properties, confirming that the correspondence of unabsorbed
(absorbed) X-ray sources to optical type I (type II) AGN is accurate
for at least 80% of the sources with spectral identification (1/3 of
the total X-ray sample).
---------------------------------------------------------
Title: A Non-axisymmetric Spherical α<SUP>2</SUP>-Dynamo
Authors: Jiang, Jie; Wang, Jing-Xiu
2006ChJAA...6..227J Altcode:
Using the Chebyshev-tau method, the generation of oscillatory
non-axisymmetric stellar magnetic fields by the α<SUP>2</SUP>-dynamo
is studied in spherical geometry. Following the boundary conditions
given by Schubert & Zhang, the spherical α<SUP>2</SUP>-dynamo
consists of a fully convective spherical shell with inner radius
r<SUB>i</SUB> and outer radius r<SUB>o</SUB>. A comparison of the
critical dynamo numbers of axisymmetric and phi-dependent modes for
different thicknesses of the convective shell and different α-profiles
leads to the following qualitative results: (i) when the angular factor
of α-profile is sin<SUP>n</SUP>θ cos θ (n = 1,2,4) the solutions of
the α<SUP>2</SUP>-dynamo are oscillatory and non-axisymmetric, (ii) the
thinner the convective shell, the more easily is the non-axisymmetric
mode excited and the higher is the latitudinal wave number, (iii)
the thickness of the outer convective shell has an effect on the
symmetries of the magnetic fields.
---------------------------------------------------------
Title: Two-Current-Sheet Reconnection Model of Interdependent Flare
and Coronal Mass Ejection
Authors: Zhang, Y. Z.; Wang, J. X.; Hu, Y. Q.
2006ApJ...641..572Z Altcode: 2006astro.ph..1231Z
Time-dependent resistive magnetohydrodynamic simulations are carried
out to study a flux rope eruption caused by magnetic reconnection
with implication in coexistent flare-CME (coronal mass ejection)
events. An early result obtained in a recent analysis of double
catastrophe of a flux rope system is used as the initial condition,
in which an isolated flux rope coexists with two current sheets:
a vertical one below and a transverse one above the flux rope. The
flux rope erupts when reconnection takes place in the current sheets,
and the flux rope dynamics depends on the reconnection sequence in the
two current sheets. Three cases are discussed: reconnection occurs (1)
simultaneously in the two current sheets, (2) first in the transverse
one and then in the vertical one, and (3) in an order opposite that of
case 2. Such a two-current-sheet reconnection exhibits characteristics
of both magnetic breakout for CME initiation and the standard flare
model. We argue that both breakout-like and tether-cutting reconnections
could be important for CME eruptions and associated surface activities.
---------------------------------------------------------
Title: Transequatorial Filament Eruption and Its Link to a Coronal
Mass Ejection
Authors: Wang, Jing-Xiu; Zhou, Gui-Ping; Wen, Ya-Yuan; Zhang, Yu-Zong;
Wang, Hua-Ning; Deng, Yuan-Yong; Zhang, Jun; Harra, Louise K.
2006ChJAA...6..247W Altcode:
We revisit the Bastille Day flare/CME Event of 2000 July 14, and
demonstrate that this flare/CME event is not related to only one single
active region (AR). Activation and eruption of a huge transequatorial
filament are seen to precede the simultaneous filament eruption and
flare in the source active region, NOAA AR 9077, and the full halo-CME
in the high corona. Evidence of reconfiguration of large-scale magnetic
structures related to the event is illustrated by SOHO EIT and Yohkoh
SXT observations, as well as, the reconstructed 3D magnetic lines
of force based on the force-free assumption. We suggest that the AR
filament in AR 9077 was connected to the transequatorial filament. The
large-scale magnetic composition related to the transequatorial filament
and its sheared magnetic arcade appears to be an essential part of the
CME parent magnetic structure. Estimations show that the filament-arcade
system has enough magnetic helicity to account for the helicity carried
by the related CMEs. In addition, rather global magnetic connectivity,
covering almost all the visible range in longitude and a huge span in
latitude on the Sun, is implied by the Nançay Radioheliograph (NRH)
observations. The analysis of the Bastille Day event suggests that
although the triggering of a global CME might take place in an AR,
a much larger scale magnetic composition seems to be the source of
the ejected magnetic flux, helicity and plasma. The Bastille Day
event is the first described example in the literature, in which a
transequatorial filament activity appears to play a key role in a
global CME. Many tens of halo-CME are found to be associated with
transequatorial filaments and their magnetic environment.
---------------------------------------------------------
Title: Large-scale source regions of earth-directed coronal mass
ejections
Authors: Zhou, G. P.; Wang, J. X.; Zhang, J.
2006A&A...445.1133Z Altcode:
Based on SOHO/MDI, EIT, Yohkoh/SXT, Hα, and other relevant
observations, we analyzed all the earth-directed halo coronal mass
ejections (CMEs) in the interval from Mar. 1997 to Dec. 2003. A
total of 288 earth-directed CMEs were studied and their associated
surface activity events identified. Unlike the previous studies that
often attributed a surface activity event or a given active region
to a CME source region, this statistical analysis puts emphasis
on the large-scale magnetic structures of CMEs, in which the
CME-associated surface activity takes place. All the CMEs are found
to be associated with large-scale source structures. The identified
large-scale structures can be grouped into four different categories:
extended bipolar regions (EBRs), transequatorial magnetic loops,
transequatorial filaments and their associated magnetic structures, and
long filaments along the boundaries of EBRs. The relative percentages
of their associated CMEs are 36%, 40%, 13%, and 11%, respectively. The
analysis indicates that CMEs are intrinsically associated with source
magnetic structures on a large spatial scale.
---------------------------------------------------------
Title: Interaction Between CME and Magnetosphere Observed by Cluster
on Nov. 6, 2001: (1) Waves Excitation
Authors: Xiao, C. J.; Song, L. T.; Pu, Z. Y.; Wang, J. X.; Liu, Z. X.;
Glassmeier, K. -H.; Balogh, A.; Reme, H.
2006IAUS..233..373X Altcode:
Very few in situ measurements so far show the details of the
interactions between CME and magnetosphere. Here we report a fortuitous
observation that the Cluster spacecraft were located at the dusk-side
magnetopause, meandering back and forth four times between the ICME
and the magnetosphere, and observed part process of the interaction
between the CME and the magnetosphere. The primarily analysis showed
that: (1) a fast ion beam other than the ambient plasma was observed
almost perpendicular to the magnetic field; (2) The left-hand-polarized
kinetic Alfvén waves excitation by the ion beam; and (3) the resonances
between the kinetic Alfvén waves and part of the beam particles lead
to the pitch angle diffusion of resonant particles and formating of
a monospheric distribution with nearly constant kinetic energy. The
wave-particle resonance may pay an important role in the energy transfer
and particle exchange across the magnetopause between the magnetosheath
and magnetosphere during the CME impulsion.
---------------------------------------------------------
Title: A Non-axisymmetric Solar Dynamo Model
Authors: Jiang, J.; Wang, J. X.
2006cosp...36..814J Altcode: 2006cosp.meet..814J
Increasing observations are becoming available about a weak but
persistent non-axisymmetric magnetic field co-exist with the dominant
axisymmetric field on the Sun It indicates non-axisymmetric magnetic
fields play an important role in the origin of solar activities A
nonlinear non-axisymmetric dynamo model is applied to try to give
an explanation of this phenomenon The model is characterized by a
solar-like internal differential rotation profile distribution of
turbulent diffusivity and the nonlinear alpha-quench in spherical
coordinate r theta phi Only the modes m 0 and 1 are considered and
numerically solved as an eigenvalue problem The stable solutions can
be found The distributions of the non-axisymmetric part of the surface
fields and the magnetic energies as a function of time for the two
modes are given too
---------------------------------------------------------
Title: CMEs driven by an eruptive prominence
Authors: Zhou, G. P.; Wang, J. X.; Zhang, J.; Chen, P. F.; Ji, H. S.;
Dere, K.
2006IAUS..233..405Z Altcode:
A clear case on Dec. 28 2002 is presented. It is about the initiation of
two successive CMEs, which were related to an eruptive prominence. In
EIT 304 Å and 195 Å observations, we found a long filament severely
twisting in a piece of its fragments, which appeared as a prominence on
Dec. 26. Then, the prominence converted its twist into writhe. Two days
later, the prominence displayed a slow rising motion for hours. There
happened internal twisting and mass motion before the prominence rapid
acceleration and final eruption. Two successive CMEs recorded by LASCO
C2 coronagraph corresponded to the early rising and the subsequently
eruptive phases of the prominence, respectively. Evidence of magnetic
reconnection, i.e., a cusp structure and post-flare loops in EUV
wavebands, and hard X-ray sources in the corona, were observed after
the prominence disruption. It appears that the kink instability and the
mass drainage in the prominence played important roles in triggering two
CMEs' initiation. We suspected that the rather impulsive acceleration
of the second CME resulted from magnetic reconnection beneath the
prominence.
---------------------------------------------------------
Title: The acceleration error estimates in LASCO CME measures
Authors: Wen, Y. Y.; Wang, J. X.; Maia, D.; Zhao, H.
2006cosp...36.1147W Altcode: 2006cosp.meet.1147W
Based on the paper that the error estimates for the height measures
grows rather fast in the first few solar radii and becomes reasonably
flat above 5 solar radii We show here how to obtain reliable
acceleration error estimates for the measures given in the catalog We
show that for the fast CMEs the uncertainties in the accelerations
are quite large when compared with the average variation within a
particular velocity subgroup of CMEs and as such only events with very
high acceleration can reliably be considered as accelerated For most
events one can not decide if a particular event has positive or negative
acceleration As a consequence and classification that separates CMEs
according to acceleration criteria will find similar distributions for
accelerated and decelerated CMEs but that only reflects the fact that
the error in determining the acceleration is quit high On average we
find that slower CMEs tend to have a positive acceleration about 1
m s 2 at heights above 5 solar radii while the 5 faster CMEs show an
average negative acceleration about -2 5 m s 2 as they propagate from
5 to 30 solar radii
---------------------------------------------------------
Title: MHD Numerical Simulation of Interdependent Flares and CMEs
Authors: Zhang, Y. Z.; Wang, J. X.; Hu, Y. Q.
2006IAUS..233..130Z Altcode:
Using time-dependent resistive magnetohydrodynamic simulations, we study
a flux rope eruption caused by magnetic reconnection with implication
in coexistent flare-CME events. Without the resistance the flux rope
system presents a double catastrophe. We use the first catastrophic
state as the initial condition, in which an isolated flux rope coexists
with two current sheets: a vertical one below and a transverse one
above the flux rope. The flux rope erupts when reconnection starts
in the current sheets, and the flux rope dynamics depends on the
reconnection sequence in the two current sheets. We obtain three cases:
reconnection occurs (1) simultaneously in the two current sheets,
(2) first in the transverse one and then in the vertical, and (3)
in an order opposite to case 2. Such a model exhibits characteristics
of both magnetic breakout model for CME initiation and standard flare
model. We argue that both breakout-like and tether-cutting reconnections
may be important for CME eruptions.
---------------------------------------------------------
Title: High-precision polarimetry design for Space Solar Telescope
Authors: Zhang, Z. Y.; Deng, Y. Y.; Hu, K. L.; Wang, D. G.; Lin,
J. B.; Sun, Y. Z.; Wang, J. X.
2006cosp...36.2864Z Altcode: 2006cosp.meet.2864Z
High polarization accuracy and high spatial resolution measurement
of solar magnetic field is the most important mission of Space Solar
Telescope Although there is no seeing induced error in the outer
space the mass flow and evolution in the solar atmosphere may become
the main source of false polarization signals To reduce this source
of polarization errors a high-speed polarimetry is required In this
paper we present our newly designed polarimeter based on high-speed
electro-optical modulation We employ Mueller Matrix to analyses
the polarization characteristics of optical elements and evaluate
the polarization errors By these discussions we also determine the
requirements to the imaging process system of SST
---------------------------------------------------------
Title: Solar proton spectrum and acceleration during the 20 January
2005 flare
Authors: Wang, R. G.; Wang, J. X.
2006cosp...36.1856W Altcode: 2006cosp.meet.1856W
A extreme solar cosmic ray event was broken out on 20 January 2005
It was not only the most intense solar energetic particle SEP event
measured by GOES satellites since 1976 but also the largest ground level
enhancement GLE recorded in neutron monitors since 1956 We present the
solar proton energy spectra of this event data from GOES measurements in
multi-channels of energy These spectra are well fit by a double power
law form It was shown that the January 20 event had the hardest energy
spectrum during solar cycle 23 and the highest fluxes for above 30 MeV
protons in past 30 years We examine variations of the spectral index
from -1 4 to -0 8 within the rise phase of proton intensity Combing
X-ray radio emission and CME observation as well as available neutron
monitor data relativistic proton acceleration and travel is discussed
It seems to imply that the first arrival relativistic protons are
released in low corona and accelerated up to GeV within minutes This
impulsive high energy process more likely associated with solar flare
instead of CME
---------------------------------------------------------
Title: Large geomagnetic storms of extreme solar event periods in
solar cycle 23
Authors: Wang, R. G.; Wang, J. X.
2006cosp...36.1855W Altcode: 2006cosp.meet.1855W
At the duration of extreme solar events solar eruption associated
with big flares or and energetic coronal mass ejections CMEs can not
only make high energy particles acceleration but also give rise to
large geomagnetic storms which have significant effects on the Earth
s environment and human life Around 14 solar cosmic ray ground level
enhancement GLE events in solar cycle 23 we examine the cosmic ray
variations solar wind speeds ion densities interplanetary magnetic
fields and geomagnetic disturbance storm time indices Dst We find that
all but one of GLEs are always followed by a geomagnetic storm with Dst
leq -50 nT within 1-5 days later Most 10 14 geomagnetic storms have Dst
index leq -100 nT suggesting that GLE event prediction of geomagnetic
storms is 93 for moderate storms and 71 for large storms More than
half 57 Dst depressions are simultaneously accompanied by cosmic ray
decreases and other Dst variabilities are without clear cosmic ray
deceases We also investigated the interplanetary plasma features during
GLE events Most geomagnetic storm correspond significant periods of
southward B z and in close to 80 of the cases that the B z was first
northward then turning southward after storm sudden commencement
SSC Plasma flow speed ion number density and interplanetary plasma
temperature near 1 AU also have a peak at interplanetary shock arrival
Solar cause and energetic particle signatures of large geomagnetic
storms are discussed
---------------------------------------------------------
Title: Homologous emerging flux and associated solar activity
Authors: Zhou, G. P.; Wang, J. X.
2006cosp...36.2906Z Altcode: 2006cosp.meet.2906Z
There are 69 GOES X-ray flares produced in the active regions ARs
10486 and 10488 during the famous Oct -Nov 2003 solar event Among them
the X28 flare in AR10488 on Nov 04 2003 may have been the largest
X-ray event since observations began in 1976 Part of the associated
large flare CMEs form magnetic clouds in the interplanetary space By
investigating the photosphere magnetograms we find that the emerging
flux in AR10486 10488 10489 10491 and 10492 appear homologous The
homologous behaviors are further confirmed by the evidence from the
sub-photospheric flow maps vertical velocity and meridional vorticity
as well as these ARs evolutions in MDI synoptic charts We also find that
there is large-scale magnetic connectivity among these ARs whether from
EIT images or from the global magnetic force lines reconstructed by
the potential extrapolation which indicate these referred ARs are not
isolated each other The ARs are probably involved in a same topological
magnetic system since we find a predominant negative helicity sign in
these ARs and their associated magnetic clouds With more analysis on
the other observations in TRACE RHESSI GOES and so on it is speculated
that the associated flares CMEs initiate during the evolutions of this
topological isolated magnetic system especially when it interacted
with the other environmental flux
---------------------------------------------------------
Title: The detection of "magnetic element"---why we need an one-meter
Space Solar Telescope
Authors: Deng, Y. Y.; Wang, J. X.; Ai, G. X.
2006cosp...36..942D Altcode: 2006cosp.meet..942D
The nature of magnetic element the elemental structure of solar
magnetic field is one of the most important mysteries in solar physics
The intrinsic properties of magnetic element such as field strength
filling factor spatial scale are unknown yet though the history of
solar magnetic measurement can go back to one hundred years ago With
the development of technology solar physicists have made a lots of
attempts to resolve the magnetic element directly For example with
the help of a set of techniques adaptive optics correlation tracker
image reconstruction etc the one-meter Swedish Solar Telescope in the
Canary Islands has nearly reached its diffraction-limit resolution
sim 0 18 630 25nm which roughly match the spatial-scale requirement
of magnetic element detection However none current-used telescope can
resolve magnetic element at this moment yet as spatial resolution is
just one of the requirements of magnetic element detection In this
paper the requirements of magnetic element detection will be discussed
By these discussions we know that the spatial resolution temporal
resolution and magnetic sensitivity are all important The proposed
Space Solar Telescope an one-meter Chinese space telescope can match
these requirements
---------------------------------------------------------
Title: Solar <SUP>3</SUP>He-rich events and abnormal enhancements
of heavy-ion isotopes accelerated in two stages
Authors: Zhang, T. X.; Wang, J. X.; Tan, A.
2005JGRA..11012111Z Altcode:
Heating and acceleration of neon (<SUP>20</SUP>Ne), magnesium
(<SUP>24</SUP>Mg), and their rare isotopes (<SUP>22</SUP>Ne and
<SUP>26</SUP>Mg) in solar <SUP>3</SUP>He-rich events are investigated
according to the two-stage acceleration mechanism. It is shown
that <SUP>20</SUP>Ne<SUP>+8</SUP>, <SUP>22</SUP>Ne<SUP>+9</SUP>,
<SUP>24</SUP>Mg<SUP>+10</SUP>, and <SUP>26</SUP>Mg<SUP>+11</SUP>
can be preferentially heated by H-cyclotron waves with a frequency
close to twice the <SUP>3</SUP>He-cyclotron frequency that
also heat <SUP>3</SUP>He, through the third harmonic cyclotron
resonance. If the initial electron temperature is in the range of
∼2-10 MK, the abundance ratios <SUP>22</SUP>Ne/<SUP>20</SUP>Ne and
<SUP>26</SUP>Mg/<SUP>24</SUP>Mg in high-energy particles due to the
second-stage acceleration can be enhanced by a factor of ∼2-6 relative
to the solar corona, which are consistent with the measurements of the
University of Maryland particle instrument on the Solar Anomalous and
Magnetospheric Particle Explorer and the Ultra Lower Energy Isotope
Spectrometer particle instrument on the Advanced Composition Explorer.
---------------------------------------------------------
Title: A New Method of Identifying 3D Null Points in Solar Vector
Magnetic Fields
Authors: Zhao, Hui; Wang, Jing-Xiu; Zhang, Jun; Xiao, Chi-Jie
2005ChJAA...5..443Z Altcode:
Employing the Poincaré index of isolated null-points in a vector field,
we worked out a mathematical method of searching for 3D null-points in
coronal magnetic fields. After introducing the relevant differential
topology, we test the method by using the analytical model of Brown
& Priest. The location of null-point identified by our method
coincides precisely with the analytical solution. Finally we apply
the method to the 3D coronal magnetic fields reconstructed from an
observed MDI magnetogram of a super-active region (NOAA 10488). We
find that the 3D null-point seems to be a key element in the magnetic
topology associated with flare occurrence.
---------------------------------------------------------
Title: Relativistic Outflow in CXOCDFS J033260.0-274748
Authors: Wang, J. X.; Wang, T. G.; Tozzi, P.; Giacconi, R.; Hasinger,
G.; Kewley, L.; Mainieri, V.; Nonino, M.; Norman, C.; Streblyanska,
A.; Szokoly, G.; Yaqoob, T.; Zirm, A.
2005ApJ...631L..33W Altcode: 2005astro.ph..8225W
In this Letter we report the detection of a strong and extremely
blueshifted X-ray absorption feature in the 1 Ms Chandra
spectrum of CXOCDFS J033260.0-274748, a quasar at z=2.579 with
L<SUB>2-10keV</SUB>~4×10<SUP>44</SUP> ergs s<SUP>-1</SUP>. The broad
absorption feature at ~6.3 keV in the observed frame can be fitted
either as an absorption edge at 20.9 keV or as a broad absorption line
at 22.2 keV rest frame. The absorber has to be extremely ionized with
an ionization parameter ξ~10<SUP>4</SUP>, and a high column density,
N<SUB>H</SUB>>5×10<SUP>23</SUP> cm<SUP>-2</SUP>. We reject the
possibility of a statistical or instrumental artifact. The most likely
interpretation is an extremely blueshifted broad absorption line or
absorption edge, due to H or He-like iron in a relativistic jetlike
outflow with bulk velocity of ~0.7c-0.8c. Similar relativistic outflows
have been reported in the X-ray spectra of several other AGNs in the
past few years.
---------------------------------------------------------
Title: Progress in the studies on a relic solar magnetic field
Authors: Song, Wen-Bin; Wang, Jing-Xiu
2005PABei..23..205S Altcode:
It is really possible that the Sun possesses a relic magnetic field
of the pre-main sequence epoch in its radiative core. Due to a stably
stratified fluid and an extremely high electrical conductivity in the
solar interior, a relic solar magnetic field can survive for a very
long time. A relic field can help us to explain many asymmetries in
solar activities, such as the north-south asymmetries of solar magnetic
activities, active longitudes and holes, low-latitude coronal holes,
Maunder minimum, etc. In addition it can affect the distribution and
evolution of solar surface magnetic field by changing the boundary
conditions of solar dynamo. This paper focuses on the introduction
of recent progress and issues in observations and theories of relic
solar magnetic field. Some unresolved problems and highlights are
also discussed.
---------------------------------------------------------
Title: A study of the north-south asymmetry of solar photospheric
magnetic flux
Authors: Song, Wen-bin; Wang, Jing-xiu; Ma, Xia
2005ChA&A..29..274S Altcode: 2005ChA&A..29..274W
Statistical characteristics of the variation of the North-South
asymmetry of solar photospheric magnetic flux in 1978-2002 are
systematically studied, and they are found to be related to the
cycle of solar activity. The degree of the asymmetry during the
minimum of solar activity is obviously higher than that during the
maximum of solar activity. Moreover, the change of magnetic flux is
always accompanied by a gradual shift of dominance from the northern
hemisphere in the ascending phase to the southern hemisphere in the
descending phase. A wavelet transform is used to make a detailed probe
of possible periodicities in the variation of the North-South asymmetry.
---------------------------------------------------------
Title: Resonant Heating of Ions by Parallel Propagating Alfvén
Waves in Solar Coronal Holes
Authors: Zhang, Tian-Xi; Wang, Jing-Xiu; Xiao, Chi-Jie
2005ChJAA...5..285Z Altcode:
Resonant heating of H, O<SUP>+5</SUP>, and Mg<SUP>+9</SUP> by parallel
propagating ion-cyclotron Alfvén waves in solar coronal holes at a
heliocentric distance is studied using the heating rate derived from
the quasilinear theory. It is shown that the particle-Alfvén-wave
interaction is a significant microscopic process. The temperatures
of the ions are rapidly increased up to the observed order in only
microseconds, which implies that simply inserting the quasilinear
heating rate into the fluid/MHD energy equation to calculate the
radial dependence of ion temperatures may cause errors as the time
scales do not match. Different species ions are heated by Alfvén
waves with a power law spectrum in approximately a mass order. To heat
O<SUP>+5</SUP> over Mg<SUP>+9</SUP> as measured by the Ultraviolet
Coronagraph Spectrometer (UVCS) in the solar coronal hole at a region
gtrsim1.9R<SUB>odot</SUB>, the energy density of Alfvén waves with a
frequency close to the O<SUP>+5</SUP>-cyclotron frequency must be at
least double of that at the Mg<SUP>+9</SUP>-cyclotron frequency. With
an appropriate wave-energy spectrum, the heating of H, O<SUP>+5</SUP>
and Mg<SUP>+9</SUP> can be consistent with the UVCS measurements in
solar coronal holes at a heliocentric distance.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Chandra Deep Field-South: Optical
spectroscopy (Szokoly+, 2004)
Authors: Szokoly, G. P.; Bergeron, J.; Hasinger, G.; Lehmann, I.;
Kewley, L.; Mainieri, V.; Nonino, M.; Rosati, P.; Giacconi, R.; Gilli,
R.; Gilmozzi, R.; Norman, C.; Romaniello, M.; Schreier, E.; Tozzi,
P.; Wang, J. X.; Zheng, W.; Zirm, A.
2005yCat..21550271S Altcode:
We present the results of our spectroscopic follow-up program of
the X-ray sources detected in the 942ks exposure of the Chandra Deep
Field-South (CDFS). A total of 288 possible counterparts were observed
at the VLT with the FORS1/FORS2 spectrographs for 251 of the 349 Chandra
sources (including three additional faint X-ray sources). Spectra and
R-band images are shown for all the observed sources and R-K colors are
given for most of them. Spectroscopic redshifts were obtained for 168
X-ray sources, of which 137 have both reliable optical identification
and redshift estimate (including 16 external identifications). The
R<24 observed sample comprises 161 X-ray objects (181 optical
counterparts), and 126 of them have unambiguous spectroscopic
identification. <P />(4 data files).
---------------------------------------------------------
Title: Double Catastrophe of Coronal Flux Rope in Quadrupolar
Magnetic Field
Authors: Zhang, Y. Z.; Hu, Y. Q.; Wang, J. X.
2005ApJ...626.1096Z Altcode:
Using a relaxation method based on time-dependent ideal
magnetohydrodynamic simulations, we find 2.5-dimensional force-free
field solutions in spherical geometry, which are associated with an
isolated flux rope embedded in a quadrupolar background magnetic
field. The background field is of Antiochos type, consisting of a
dipolar and an octopolar component with a neutral point somewhere in
the equatorial plane. The flux rope is characterized by its magnetic
fluxes, including the annular flux Φ<SUB>p</SUB> and the axial
magnetic flux Φ<SUB>ϕ</SUB>, and its geometric features described
by the height of the rope axis and the length of the vertical current
sheet below the rope. It is found that for a given Φ<SUB>p</SUB>, the
force-free field exhibits a complex catastrophic behavior with respect
to increasing Φ<SUB>ϕ</SUB>. There exist two catastrophic points,
and the catastrophic amplitude, measured by the jump in the height
of the rope axis, is finite for both catastrophes. As a result, the
flux rope may levitate stably in the corona after catastrophe, with a
transverse current sheet above and a vertical current sheet below. The
magnetic energy threshold for the two successive catastrophes are found
to be larger than the corresponding partly open field energy. We argue
that it is the transverse current sheet formed above the flux rope that
provides a downward Lorentz force on the flux rope and thus keeps the
rope levitating stably in the corona.
---------------------------------------------------------
Title: Progress in solar dynamo theories
Authors: Jiang, Jie; Wang, Jing-Xiu
2005PABei..23..121J Altcode:
The solar dynamo, which explains the origin and the evolution of
all magnetic fields observed on the sun, is the fundamental and
essential question of Solar Physics. Scientific inquiry into the
question is more than an academic exercise. It is important to the
development of space technology and the prediction of terrestrial
climate. With the development of helioseismology, the solar dynamo
has made great progresses. Staring from the observation, the paper
summarizes some observations on the solar surface and the dynamic
construction interior. The basic theories and the central models are
introduced. Some unsolved problems are discussed.
---------------------------------------------------------
Title: Two Extreme Double-peaked Line Emitters in the Sloan Digital
Sky Survey
Authors: Wang, T. -G.; Dong, X. -B.; Zhang, X. -G.; Zhou, H. -Y.;
Wang, J. -X.; Lu, Y. -J.
2005ApJ...625L..35W Altcode: 2005astro.ph..4320W
Double-peaked Balmer lines have been observed in about 150 active
galactic nuclei and were interpreted preferentially as emission from
relativistic accretion disks. We report the discovery of extreme
double-peaked lines in SDSS J0942+0900 and SDSS J1417+6141. The FWHM
of the Hα line, ~=40,600 km s<SUP>-1</SUP>, in the first object is
almost twice as large as the broadest previously known. By comparing
the line profile with accretion disk models, we find that most of the
line flux is emitted from a narrow annulus around 100r<SUB>g</SUB> in
SDSS J0942+0900, and from a disk with radii between 100r<SUB>g</SUB>
and 400r<SUB>g</SUB> in SDSS J1417+6141. This is the first time that
an accretion disk at radii below 100r<SUB>g</SUB> has been directly
probed through optical emission lines. A certain asymmetry in the
disk is required for both objects. Another, much weaker, broad Hα
component (W<SUB>λ</SUB>~20 Å and FWHM ~4000 km s<SUP>-1</SUP>) is
also detected in both objects. Both objects show weak radio emission
and strong high-ionization narrow lines.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Photometric redshifts of X-ray
sources in CDF-S (Zheng+, 2004)
Authors: Zheng, W.; Mikles, V. J.; Mainieri, V.; Hasinger, G.; Rosati,
P.; Wolf, C.; Norman, C.; Szokoly, G.; Gilli, R.; Tozzi, P.; Wang,
J. X.; Zirm, A.; Giacconi, R.
2005yCat..21550073Z Altcode:
Based on the photometry of 10 near-ultraviolet, optical, and
near-infrared bands of the Chandra Deep Field-South, we estimate the
photometric redshifts for 342 X-ray sources, which constitute ~99%
of all the detected X-ray sources in the field. <P />(1 data file).
---------------------------------------------------------
Title: Correlation Heights of the Sources of Solar Ultraviolet
Emission Lines in a Quiet-Sun Region
Authors: Tu, Chuan-Yi; Zhou, Cheng; Marsch, Eckart; Wilhelm, Klaus;
Zhao, Liang; Xia, Li-Dong; Wang, Jing-Xiu
2005ApJ...624L.133T Altcode:
The radiance and Doppler-velocity maps of the emission lines of Si
II, C IV, and Ne VIII obtained in a quiet region of the Sun by SUMER
(Solar Ultraviolet Measurements of Emitted Radiation) are correlated
with the vertical component, B<SUB>z</SUB>, of the magnetic field
vector as extrapolated, by means of a force-free field model, from
the photospheric magnetic field measured by MDI (Michelson Doppler
Imager). It is found that, with increasing vertical height, each of the
correlation coefficients initially increases to a maximum value before
it decreases again. The height corresponding to this maximum is called
the correlation height. For the data sets selected from a quiet-Sun
region, the correlation heights of Si II and C IV are near 2 Mm,
and for Ne VIII near 4 Mm. At their correlation heights, the averaged
square root of the radiance of the emission lines of Si II and C IV,
considered as a proxy of the plasma density, has a linear relationship
with B<SUB>z</SUB>. This result supports the empirical concept that the
solar transition region is very thin and still affected by frozen-in
convection. A way for improvement of such studies is also outlined.
---------------------------------------------------------
Title: Solar Wind Origin in Coronal Funnels
Authors: Tu, Chuan-Yi; Zhou, Cheng; Marsch, Eckart; Xia, Li-Dong;
Zhao, Liang; Wang, Jing-Xiu; Wilhelm, Klaus
2005Sci...308..519T Altcode:
The origin of the solar wind in solar coronal holes has long been
unclear. We establish that the solar wind starts flowing out of the
corona at heights above the photosphere between 5 megameters and 20
megameters in magnetic funnels. This result is obtained by a correlation
of the Doppler-velocity and radiance maps of spectral lines emitted
by various ions with the force-free magnetic field as extrapolated
from photospheric magnetograms to different altitudes. Specifically,
we find that Ne<SUP>7+</SUP> ions mostly radiate around 20 megameters,
where they have outflow speeds of about 10 kilometers per second,
whereas C<SUP>3+</SUP> ions with no average flow speed mainly radiate
around 5 megameters. Based on these results, a model for understanding
the solar wind origin is suggested.
---------------------------------------------------------
Title: An Overdensity of Lyα Emitters at Redshift z~5.7 near the
Hubble Ultra Deep Field
Authors: Wang, J. X.; Malhotra, S.; Rhoads, J. E.
2005ApJ...622L..77W Altcode: 2005astro.ph..1479W
We have identified an obvious and strong large-scale structure at
redshift z~5.75 in a wide (31<SUP>'</SUP>×33<SUP>'</SUP>) field,
narrowband survey of the Chandra Deep Field-South region. This structure
is traced by 17 candidate Lyα emitters, among which 12 are found in an
823 nm filter (corresponding to Lyα at z=5.77+/-0.03) and five in an
815 nm image (z=5.70+/-0.03). The Lyα emitters in both redshift bins
are concentrated in one quadrant of the field. The Hubble Ultra Deep
Field, the Chandra Deep Field-South, and the Great Observatories Origins
Deep Survey-South fields all lie near the edge of this overdensity
region. Our results are consistent with reports of an overdensity in
the Ultra Deep Field region at z~5.9. This structure is the highest
redshift overdensity found so far.
---------------------------------------------------------
Title: Strong Ca II Absorption Lines in the Reddened Quasar SDSS
J2339-0912: Evidence of the Collision/Merger in the Host Galaxy?
Authors: Wang, T. G.; Dong, X. B.; Zhou, H. Y.; Wang, J. X.
2005ApJ...622L.101W Altcode: 2005astro.ph..4319W
We report the detection of strong Ca II/Mg II absorption lines
at the quasar redshift in the narrow-line quasar SDSS J2339-0912
(z=0.6604). The quasar exhibits strong Fe II, a small Balmer emission
line width, and a very red B-K<SUB>s</SUB> color. Both the optical
continuum and broad emission lines are reddened by SMC-like dust of
E(B-V)~=1.0 mag, while its near-infrared color (J-K<SUB>s</SUB>=1.60)
shows little reddening. The Ca II absorption lines are saturated and
resolved with an FWHM of 362 km s<SUP>-1</SUP> and an equivalent width
of W<SUB>CaIIK</SUB>=4.2 Å (in the source rest frame). Mg II absorption
lines are also saturated and have a similar line width. The line profile
and the fact that there is no evidence of starlight from the host galaxy
suggest that these absorption lines are not of a stellar origin. The
ratio of column density of Ca II to that of dust is consistent with
that of the interstellar medium (ISM) in our Galaxy. We suggest that
both the heavy reddening and the large absorption line width are due
to the highly disturbed ISM on the line of sight toward the quasar and
that the disturbance is caused by a galaxy collision or even merger
in the quasar host galaxy.
---------------------------------------------------------
Title: Cross-correlations between CMEs and other Solar Activity
Indices
Authors: Song, W. B.; Wang, J. X.
2005IAUS..226..213S Altcode:
Using the list of CMEs observed by SOHO/LASCO, we compile a daily CME
counts from January 1996 to December 2003. Cross-correlations between
the CME counts and other three solar activity indices, i.e., flare
index, sunspot number, and photospheric magnetic flux, are examined
in both real and Fourier spaces. We find that correlations are all
significant in real space, but only photospheric magnetic flux has
good correlation with CME counts in Fourier space. Typical periods of
CME occurrence are presented and discussed.
---------------------------------------------------------
Title: CMEs and Flux Appearance in the Periphery of Two Unipolar
Sunspots
Authors: Yang, X. L.; Song, W. B.; Zhou, G. P.; Zhang, J.; Wang, J. X.
2005IAUS..226..215Y Altcode:
A class of large-scale magnetic compositions have been identified to
be CME-prolific, which is characterized by a huge unipolar sunspot
appearing in a large-scale extended bipolar region in synoptic
magnetic charts. To understand the CMEs' origin and the nature of flux
appearance, we scrutinize the long time-sequence of MDI magnetograms
of high-resolution mode for super active region AR9236. Two types of
magnetic features are clearly identified. They are moving magnetic
features (MMFs) emanated radially from the penumbral boundary and
emerging flux regions (EFRs) whose growing opposite polarities rotate
out from the inner boundary of sunspot moat along helical paths
in opposite directions. The interaction between the MMFs and EFRs
often creates multi-fold magnetic neutral lines where the flare/CMEs
initiated.
---------------------------------------------------------
Title: The north-south asymmetry of solar photospheric magnetic flux
Authors: Song, W. B.; Wang, J. X.; Ma, X.
2005AcASn..46...19S Altcode:
The north-south asymmetry of solar photospheric magnetic flux is studied
during years 1978-2002, finding that it has been relative to the solar
activity cycle and peaked about the time of solar minimum. The dominance
of solar activity has started to shift during the solar maximum from
the northern hemisphere to the southern one. And its periodicities
have been also discussed in detail with the wavelet transform.
---------------------------------------------------------
Title: Wavelet analysis of photospheric magnetic flux
Authors: Song, W. B.; Wang, J. X.
2005AdSpR..35..341S Altcode:
We link 342 NSO/Kitt Peak synoptic charts during 1978 to 2003 one by
one in time order and reconstruct a daily sequence of photospheric
magnetic flux (PMF). By using wavelet transform (WT) some typical
mid-term periodicities of PMF are identified, such as 1.38-year,
332-, 275- and 158-day periods. We discuss briefly their temporal
evolutions and mutual relations in this paper. For a comparison with
another solar general index, we also analyze the periodicities of total
solar irradiance (TSI) with the same method. We find the wavelet power
spectra of such two sequences are very similar. Therefore, we think
PMF and TSI may have some common physical origins.
---------------------------------------------------------
Title: The Chandra Deep Field-South: Optical Spectroscopy. I.
Authors: Szokoly, G. P.; Bergeron, J.; Hasinger, G.; Lehmann, I.;
Kewley, L.; Mainieri, V.; Nonino, M.; Rosati, P.; Giacconi, R.; Gilli,
R.; Gilmozzi, R.; Norman, C.; Romaniello, M.; Schreier, E.; Tozzi,
P.; Wang, J. X.; Zheng, W.; Zirm, A.
2004ApJS..155..271S Altcode: 2003astro.ph.12324S
We present the results of our spectroscopic follow-up program of the
X-ray sources detected in the 942 ks exposure of the Chandra Deep
Field-South (CDFS). A total of 288 possible counterparts were observed
at the VLT with the FORS1/FORS2 spectrographs for 251 of the 349 Chandra
sources (including three additional faint X-ray sources). Spectra and
R-band images are shown for all the observed sources and R-K colors are
given for most of them. Spectroscopic redshifts were obtained for 168
X-ray sources, of which 137 have both reliable optical identification
and redshift estimate (including 16 external identifications). The
R<24 observed sample comprises 161 X-ray objects (181 optical
counterparts), and 126 of them have unambiguous spectroscopic
identification. There are two spikes in the redshift distribution,
predominantly populated by type 2 active galactic nuclei (AGNs)
but also type 1 AGN and X-ray normal galaxies: the one at z=0.734 is
fairly narrow (in redshift space) and comprises two clusters/groups
of galaxies centered on extended X-ray sources, the second one at
z=0.674 is broader and should trace a sheetlike structure. The type
1 and type 2 populations are clearly separated in X-ray/optical
diagnostics involving parameters sensitive to absorption/reddening:
X-ray hardness ratio (HR), optical/near-IR color, soft X-ray flux,
and optical brightness. Nevertheless, these two populations cover
similar ranges of hard X-ray luminosity and absolute K magnitude,
thus trace similar levels of gravitational accretion. Consequently, we
introduce a new classification based solely on X-ray properties, HR,
and X-ray luminosity, consistent with the unified AGN model. This
X-ray classification uncovers a large fraction of optically
obscured, X-ray-luminous AGNs missed by the classical optical
classification. We find a similar number of X-ray type 1 and type 2
QSOs [L<SUB>X</SUB>(0.5-10keV)>10<SUP>44</SUP> ergs s<SUP>-1</SUP>]
at z>2 (13 sources with unambiguous spectroscopic identification);
most X-ray type 1 QSOs are bright, R<~24, whereas most X-ray type
2 QSOs have R>~24, which may explain the difference with the CDFN
results as few spectroscopic redshifts were obtained for R>24 CDFN
X-ray counterparts. There are X-ray type 1 QSOs down to z~0.5, but
a strong decrease at z<2 in the fraction of luminous X-ray type 2
QSOs may indicate a cosmic evolution of the X-ray luminosity function
of the type 2 population. An X-ray spectral analysis is required to
confirm this possible evolution. The red color of most X-ray type 2
AGNs could be due to dust associated with the X-ray absorbing material
and/or a substantial contribution of the host galaxy light. The latter
can also be important for some redder X-ray type 1 AGNs. There is
a large population of EROs (R-K>5) as X-ray counterparts, and
their fraction strongly increases with decreasing optical flux, up
to 25% for the R>=24 sample. They cover the whole range of X-ray
hardness ratios, comprise objects of various classes (in particular
a high fraction of z>~1 X-ray absorbed AGNs, but also elliptical
and starburst galaxies) and more than half of them should be fairly
bright X-ray sources [L<SUB>X</SUB>(0.5-10keV)>10<SUP>42</SUP> ergs
s<SUP>-1</SUP>]. Photometric redshifts will be necessary to derive
the properties and evolution of the X-ray selected EROs. <P />Based
on observations collected at the European Southern Observatory, Chile
[ESO no. 66.A-0270(A) and 67.A-0418(A)].
---------------------------------------------------------
Title: Low frequency radio signatures of coronal mass ejections
Authors: Wen, Ya-Yuan; Wang, Jing-Xiu
2004PABei..22..284W Altcode:
Coronal mass ejections (CMEs) are the most spectacular phenomena
of solar activities, and the solar events with the largest spatial
scale. CMEs are often accompanied with other solar activities. Many
solar phenomena are believed to have direct or indirect correlations
with CMEs, such as solar flares, prominence eruption, helmet streamers,
high-speed solar winds, coronal and interplanetary shock waves,
and so on. Radio observations are an important complementary tool
to study CMEs. Multi-frequency radio measurements not only study
the initiation of CMEs, but also get more information on triggering
mechanism of CMEs. In the present paper, we summarize the relationships
between CMEs and low frequency radio bursts with the observational
instruments and the radio signatures of CMEs being introduced
and analyzed. The initiation mechanism and some open questions are
discussed as well. Finally we claim that studies of CMEs must base on
the multi-species data in all electromagnetic radiation wavelengths.
---------------------------------------------------------
Title: Photometric Redshift of X-Ray Sources in the Chandra Deep
Field-South
Authors: Zheng, W.; Mikles, V. J.; Mainieri, V.; Hasinger, G.; Rosati,
P.; Wolf, C.; Norman, C.; Szokoly, G.; Gilli, R.; Tozzi, P.; Wang,
J. X.; Zirm, A.; Giacconi, R.
2004ApJS..155...73Z Altcode: 2004astro.ph..6482Z
Based on the photometry of 10 near-ultraviolet, optical, and
near-infrared bands of the Chandra Deep Field-South, we estimate the
photometric redshifts for 342 X-ray sources, which constitute ~99%
of all the detected X-ray sources in the field. The models of spectral
energy distribution are based on galaxies and a combination of power-law
continuum and emission lines. Color information is useful for source
classifications: type I active galactic nuclei (AGNs) show nonthermal
spectral features that are distinct from galaxies and type II AGNs. The
hardness ratio in X-ray and the X-ray-to-optical flux ratio are also
useful discriminators. Using rudimentary color separation techniques, we
are able to further refine our photometric redshift estimations. Among
these sources, 173 have reliable spectroscopic redshifts, which we use
to verify the accuracy of photometric redshifts and to modify the model
inputs. The average relative dispersion in redshift distribution is ~8%,
among the most accurate for photometric surveys. The high reliability
of our results is attributable to the high quality and broad coverage
of data as well as the applications of several independent methods and
a careful evaluation of every source. We apply our redshift estimations
to study the effect of redshift on broadband colors and to study the
redshift distribution of AGNs. Our results show that both the hardness
ratio and U-K color decline with redshift, which may be the result
of a K-correction. The number of type II AGNs declines significantly
at z>2 and that of galaxies declines at z>1. However, the
distribution of type I AGNs exhibits less redshift dependence. As
well, we observe a significant peak in the redshift distribution at
z=0.6. We demonstrate that our photometric redshift estimation produces
a reliable database for the study of X-ray luminosity of galaxies and
AGNs. <P />Based on observations performed at the European Southern
Observatory and observations with the NASA/ESA Hubble Space Telescope,
obtained at the Space Telescope Science Institute, which is operated
by the Association of Universities of Research in Astronomy, Inc.,
under NASA contract NAS5-26555.
---------------------------------------------------------
Title: Double-Power-Law Energy Spectra of Electrons from Solar
<SUP>3</SUP>He-rich Events
Authors: Zhang, T. X.; Wang, J. X.
2004ApJ...613L.165Z Altcode:
A possible explanation is proposed for the double-power-law energy
spectrum of electrons from solar <SUP>3</SUP>He-rich events. According
to the two-stage acceleration model that was developed by Zhang
for the heating and acceleration of ions and electrons in solar
<SUP>3</SUP>He-rich events, the energy spectrum of electrons in
the thermal to power law energy range is derived. It is shown that
the electron flux generally includes a thermal component at low
energies and a nonthermal component with a power-law spectrum at high
energies. To have the double-power-law energy spectrum of electrons
at the high energies, three empirical models are proposed in terms of
the dependences of the spectral power index, the electron temperature,
and the threshold energy on the electron energy. The numerical result
obtained by this study for the energy spectrum of electrons at energies
~1-200 keV fits very well with the double-power-law spectrum measurement
given by Reames, von Rosenvinge, & Lin.
---------------------------------------------------------
Title: Identifying High-Redshift Active Galactic Nuclei Using X-Ray
Hardness
Authors: Wang, J. X.; Malhotra, S.; Rhoads, J. E.; Norman, C. A.
2004ApJ...612L.109W Altcode: 2004astro.ph..5499W
The X-ray color (hardness ratio) of optically undetected X-ray sources
can be used to distinguish obscured active galactic nuclei (AGNs) at
low and intermediate redshift from viable high-redshift (i.e., z>5)
AGN candidates. This will help determine the space density, ionizing
photon production, and X-ray background contribution of the earliest
detectable AGNs. High-redshift AGNs should appear soft in X-rays,
with hardness ratio HR~-0.5, even if there is strong absorption
by a hydrogen column density N<SUB>H</SUB> up to 10<SUP>23</SUP>
cm<SUP>-2</SUP>, simply because the absorption redshifts out of the
soft X-ray band in the observed frame. Here the X-ray hardness ratio
is defined as HR=(H-S)/(H+S), where S and H are the soft and hard band
net counts detected by Chandra. High-redshift AGNs that are Compton
thick (N<SUB>H</SUB>>~10<SUP>24</SUP> cm<SUP>-2</SUP>) could have
HR~0.0 at z> 5. However, these should be rare in deep Chandra
images, since they have to be >~10 times brighter intrinsically,
which implies a >~100 times drop in their space density. Applying
the hardness criterion (HR<0.0) can filter out about 50% of the
candidate high-redshift AGNs selected from deep Chandra images.
---------------------------------------------------------
Title: X-Ray Nondetection of the Lyα Emitters at z~4.5
Authors: Wang, J. X.; Rhoads, J. E.; Malhotra, S.; Dawson, S.; Stern,
D.; Dey, A.; Heckman, T. M.; Norman, C. A.; Spinrad, H.
2004ApJ...608L..21W Altcode: 2004astro.ph..4611W
The Lyα emitters found at z~4.5 by the Large Area Lyman Alpha (LALA)
survey have high equivalent widths in the Lyα line, which can be
produced by either narrow-lined active galactic nuclei (AGNs) or by
stellar populations with a very high proportion of young, massive
stars. To investigate the AGN scenario, we obtained two deep Chandra
exposures to study the X-ray nature of the Lyα emitters. The 172
ks deep Chandra image on the LALA Boötes field was presented in
a previous paper, and in this Letter we present a new Chandra deep
exposure (174 ks) on the LALA Cetus field, which doubled our sample of
X-ray-imaged Lyα sources and imaged the brightest source among our Lyα
emitters. None of the 101 Lyα sources covered by two Chandra exposures
were detected individually in X-rays, with a 3 σ limiting X-ray flux of
F<SUB>0.5-10.0keV</SUB><3.3×10<SUP>-16</SUP> ergs cm<SUP>-2</SUP>
s<SUP>-1</SUP> for on-axis targets. The sources remain undetectable
in the stacked image, implying a 3 σ limit to the average luminosity
of L<SUB>2-8keV</SUB><2.8×10<SUP>42</SUP> ergs s<SUP>-1</SUP>. The
resulting X-ray to Lyα ratio is greater than 21 times lower than the
ratios for known high-redshift type II quasars. Together with optical
spectra obtained at Keck, we conclude that no evidence of AGN activity
was found among our Lyα emitters at z~4.5.
---------------------------------------------------------
Title: Deep Chandra image in the Bootes Field
Authors: Wang, J. X.; Malhotra, S.; Rhoads, J. E.; Brown, M. J. I.;
Dey, A.; Jannuzi, B. T.; Dawson, S.; Spinrad, H.; Heckman, T. M.;
Norman, C. A.; Stern, D.; Tiede, G. P.; Tozzi, P.
2004AAS...204.4814W Altcode: 2004BAAS...36..748W
A 172 ks long Chandra exposure was carried out in the LALA-Bootes field
and a similar one for the LALA cetus field. These exposure were deep
enough to detect LALA sources, if they were type-II quasars. Lyman-alpha
emitters found with LALA show high equivalent widths and AGN phenomenon
is one explanation. A total of 101 Ly-alpha emitters are covered by the
two Chandra images. No Ly-alpha emitters are detected individually or
in the co-added X-ray images. Our analysis indicates that fewer than
4.8 Ly-alpha emitters could be possible AGNs based on the upper limit
of their average X-ray to Ly-alpha ratio. The two X-ray images are
among the deepest taken by Chandra, with a total of 348 X-ray sources
detected, similar to the number of X-ray sources in Chandra Deep Field
South. We also see field-to-field variations of the hard X-ray source
counts in different Chandra fields, due to large scale structure.
---------------------------------------------------------
Title: Lyman Alpha Galaxies at High Redshift
Authors: Rhoads, J. E.; Malhotra, S.; Dawson, S.; Dey, A.; Jannuzi,
B. T.; Spinrad, H.; Stern, D.; Wang, J. X.; Xu, C.; Brown, M. J. I.;
Landes, E.
2004AAS...204.4803R Altcode: 2004BAAS...36..746R
Because strong Lyman alpha emission is expected from young star
forming galaxies at high redshift, it offers an efficient tool for
identifying these galaxies. The Large Area Lyman Alpha survey is one
of the first and largest successful searches for Lyman alpha emitting
galaxies at high redshift. In the LALA Bootes field (which lies within
the NOAO Deep Wide-Field Survey's Bootes field) we have obtained deep
narrowband images covering 1/3 square degree in each of eight filters,
sampling redshifts z=4.5, 5.7, and 6.5. We focus here on the higher
redshift windows, where we have confirmed a luminous Lyman alpha
emitting galaxy at z=6.535 and several others in the z=5.7 window. We
discuss the physical properties of these objects, including their
contribution to star formation rates and metal production. We also
discuss the implications of Lyman alpha galaxy observations at z=6.5
for reionization.
---------------------------------------------------------
Title: Identifying high redshift AGNs from X-ray colors
Authors: Wang, J. X.; Rhoads, J. E.; Malhotra, S.; Norman, C. A.
2004AAS...204.4407W Altcode: 2004BAAS...36Q.732W
The X-ray color (hardness ratio) can be used to select high redshift
active galactic nuclei (AGNs) among the x-ray selected, optically
blank candidates. High redshift AGNs should appear soft in X-ray with
hardness ratio HR ∼ -0.5, even if there is strong absorption with
N<SUB>H</SUB> up to 10<SUP>23</SUP> cm<SUP>-2</SUP>, simply because
the absorption redshifts out of the soft X-ray band in the observed
frame. Here the X-ray hardness ratio is defined as HR= (H-S)/(H+S),
where S and H are the soft and hard band net counts detected by
Chandra. High redshift AGNs that are Compton thick (N<SUB>H</SUB> >=
10<SUP>24</SUP> cm<SUP>-2</SUP>) could have HR ∼ 0.0, however, these
should be rare in deep Chandra images, since they have to be ∼ 10
times brighter intrinsicly, which leads to ∼ 100 times drop in their
space density. All known z > 4 AGNs show soft x-ray colors. Applying
the hardness criterion (HR < 0.0) can filter out about 50% of the
candidate high redshift AGNs selected from deep Chandra images.
---------------------------------------------------------
Title: Investigation for the cosmic ray ground level enhancements
during solar cycle 23
Authors: Wang, R. G.; Wang, J. X.
2004cosp...35.2410W Altcode: 2004cosp.meet.2410W
Major solar energetic particle (SEP) events associated with large
solar flares can give rise to the cosmic ray ground level enhancements
(GLEs). Up to December 2003 during solar activity cycle 23, 12 GLEs
(Number from 55 to 66) have been recorded by the worldwide network
of neutron monitors (NMs) in the 87 solar proton events (with peak
flux exceeding 10 {(cm^2 sec ster)}<SUP>-1</SUP> for more than 10
MeV solar protons ). Eeight of the 12 GLEs (67%) are originated from
southern hemisphere and 10 of the 12 GLEs (83%) are originated from
western hemisphere. Each GLE is corresponded by a solar coronal mass
ejection (CME) which had the potential of producing disturbances to the
geospace. Among the 12 relevant CMEs 8 large ones should be responsible
for the 8 major geomagnetic storms (defined by disturbance storm time
index ≤ -100 nT). The largest 3 geomagnetic storms (Dst≤ -300 nT)
correspond to the 3 GLEs (No.59, No.65 and No.66) which have great
proton flux with energy > 10 MeV. It seems to imply that the solar
proton events having great proton flux are more likely to bring major
geomagnetic storms. Furthermore, solar proton event with high flux is
not a condition for creating GLE. Some proposal factors are discussed
for GLE production.
---------------------------------------------------------
Title: The 172 ks Chandra Exposure of the LALA Bootes Field: X-Ray
Source Catalog
Authors: Wang, J. X.; Malhotra, S.; Rhoads, J. E.; Brown, M. J. I.;
Dey, A.; Heckman, T. M.; Jannuzi, B. T.; Norman, C. A.; Tiede, G. P.;
Tozzi, P.
2004AJ....127..213W Altcode: 2003astro.ph..9705W
We present an analysis of a deep, 172 ks Chandra observation of
the Large Area Lyman Alpha survey (LALA) Bootes field, obtained
with the Advanced CCD Imaging Spectrometer (ACIS-I) on board the
Chandra X-Ray Observatory. This is one of the deepest Chandra images
of the extragalactic sky; only the 2 Ms Chandra Deep Field North
(CDF-N) and 1 Ms Chandra Deep Field South (CDF-S) are substantially
deeper. In this paper we present the X-ray source catalog obtained
from this image, along with an analysis of source counts and optical
identifications. The X-ray image is composed of two individual
observations obtained in 2002 and reaches 0.5-2.0 and 2.0-10.0 keV
flux limits of 1.5×10<SUP>-16</SUP> and 1.0×10<SUP>-15</SUP> ergs
cm<SUP>-2</SUP> s<SUP>-1</SUP>, respectively, for point sources near
the aim point. A total of 168 X-ray sources were detected: 160 in the
0.5-7.0 keV band, 132 in the 0.5-2.0 keV band, and 111 in the 2.0-7.0
keV band. The X-ray source counts were derived and compared with those
from other Chandra deep surveys; the hard X-ray source density of the
LALA Bootes field is 33% higher than that of CDF-S at the flux level of
2.0×10<SUP>-15</SUP> ergs cm<SUP>-2</SUP> s<SUP>-1</SUP>, confirming
the field-to-field variances of the hard-band source counts reported by
previous studies. The deep exposure resolves >~72% of the 2.0-10.0
keV X-ray background. Our primary optical data are R-band imaging from
the NOAO Deep Wide-Field Survey (NDWFS), with a limiting magnitude of
R=25.7 (Vega, 3 σ, and 4" diameter aperture). We have found optical
counterparts for 152 of the 168 Chandra sources (90%); 144 of these
are detected in the R-band image, and eight have optical counterparts
in other bands (either B<SUB>W</SUB>, V, I, or z'). Among the R-band
nondetected sources, not more than 11 of them can possibly be at z>5,
based on the hardness ratios of their X-ray emission and nondetections
in bluer bands (B<SUB>W</SUB>, V). The majority (~76%) of the X-ray
sources are found to have log(f<SUB>X</SUB>/f<SUB>R</SUB>) within
0.0+/-1 these are believed to be AGNs. Most of the X-ray-faint/optically
bright sources [log(f<SUB>X</SUB>/f<SUB>R</SUB>)<-1.0] are optically
extended; these are low-z normal galaxies or low-luminosity AGNs. There
is also a population of sources that are X-ray overluminous for their
optical magnitudes [log(f<SUB>X</SUB>/f<SUB>R</SUB>)>1.0], which
are harder in X-ray and are probably obscured AGNs.
---------------------------------------------------------
Title: Reconnection in the lower solar atmosphere and coronal mass
ejections
Authors: Wang, J. X.
2004cosp...35.3644W Altcode: 2004cosp.meet.3644W
In 1985 a phenomenon in solar physics, named as magnetic flux
cancellation, was first described in details by Livi, Wang, Martin
(1995). Since then, it has been revealed that flux cancellation is
intrinsically correlated to the most, if not all, types of solar
activity, such as flare, filament formation and eruption in active
regions, and ubiquitous small-scale activity, e.g., X-ray bright
points, explosive events, mini-filament eruptions and so on. Only
recently, it was discovered that flux cancellation appeared to be
a very key magnetic evolution leading to the initiation of coronal
mass ejections (Zhang et al. 2001; Zhang and Wang, 2001; Zhang, Wang,
Nitta, 2001). On the other hand, the nature of flux cancellation has
become a topic of persistent interests and debates. In this talk,
we review the observational properties of magnetic flux cancellation
and the relevant theoretical studies, and present observations of
flux cancellation from vector magnetograph in CME associated source
regions. Then, we demonstrate that at least some well-observed flux
cancellation by vector magnetograph fits nicely the scenario of magnetic
reconnection in the lower solar atmosphere, i.e., the partially ionized
plasma. It is suggested that the magnetic reconnection in the lower
solar atmosphere is the key elements in the CME magnetism.
---------------------------------------------------------
Title: Periodicities in solar coronal mass ejections
Authors: Lou, Yu-Qing; Wang, Yu-Ming; Fan, Zuhui; Wang, Shui; Wang,
Jing Xiu
2003MNRAS.345..809L Altcode: 2003astro.ph..7277L
Mid-term quasi-periodicities in solar coronal mass ejections (CMEs)
during the most recent solar maximum cycle 23 are reported here for the
first time using the four-year data (1999 February 5 to 2003 February
10) of the Large Angle Spectrometric Coronagraph on board the Solar and
Heliospheric Observatory. In parallel, mid-term quasi-periodicities in
solar X-ray flares (class >M5.0) from the Geosynchronous Operational
Environment Satellites and in daily averages of Ap index for geomagnetic
disturbances from the World Data Center at the International Association
for Geomagnetism and Aeronomy are also examined for the same four-year
time-span. By Fourier power spectral analyses, the CME data appear
to contain significant power peaks at periods of ~358 +/- 38, ~272
+/- 26, ~196 +/- 13 d and so forth, while, except for the ~259 +/-
24 d period, X-ray solar flares of class >~M5.0 show the familiar
Rieger-type quasi-periods at ~157 +/- 11, ~122 +/- 5, ~98 +/- 3 d and
shorter ones down to ~34 +/- 0.5 d. In the data of daily averages of Ap
index, the two significant peaks at periods ~273 +/- 26 and ~187 +/-
12 d (the latter is most prominent) could imply that CMEs (periods
at ~272 +/- 26 and ~196 +/- 13 d) may be proportionally correlated
with quasi-periodic geomagnetic storm disturbances. At the speculative
level, the ~138 +/- 6 d period might imply that X-ray flares of class
>~M5.0 (period at ~157 +/- 11 d) drive certain types of geomagnetic
disturbances; the ~28 +/- 0.2 d periodicity is most likely caused by
recurrent high-speed solar winds at the Earth's magnetosphere. For
the same three data sets, we further perform Morlet wavelet analysis
to derive period-time contours and identify wavelet power peaks and
time-scales at the 99 per cent confidence level for comparisons. Several
conceptual aspects of possible equatorially trapped Rossby-type waves
at and beneath the solar photosphere are discussed.
---------------------------------------------------------
Title: On the Latitudinal Distribution of Sunspot Groups over a
Solar Cycle
Authors: Li, K. J.; Wang, J. X.; Zhan, L. S.; Yun, H. S.; Liang,
H. F.; Zhao, H. J.; Gu, X. M.
2003SoPh..215...99L Altcode:
The latitudinal distribution of sunspot groups over a solar cycle
is investigated. Although individual sunspot groups of a solar cycle
emerge randomly at any middle and low latitude, the whole latitudinal
distribution of sunspot groups of the cycle is not stochastic and,
in fact, can be represented by a probability density function of the
Γ distribution having maximum probability at about 15.5°. The maximum
amplitude of a solar cycle is found to be positively correlated against
the number of sunspot groups at high latitude (≥35°) over the cycle,
as well as the mean latitude. Also, the relation between the asymmetry
of sunspot groups and its latitude is investigated, and a pattern of
the N-S asymmetry in solar activity is suggested.
---------------------------------------------------------
Title: A Fluid Dynamics Approach for the Computation of Nonlinear
Force-Free Magnetic Field
Authors: Li, Jing-Qun; Wang, Jing-Xiu; Wei, Feng-Si
2003ChJAA...3..247L Altcode:
Inspired by the analogy between the magnetic field and velocity field
of incompressible fluid flow, we propose a fluid dynamics approach for
computing nonlinear force-free magnetic fields. This method has the
advantage that the divergence-free condition is automatically satisfied,
which is a sticky issue for many other algorithms, and we can take
advantage of modern high resolution algorithms to process the force-free
magnetic field. Several tests have been made based on the well-known
analytic solution proposed by Low & Lou. The numerical results
are in satisfactory agreement with the analytic ones. It is suggested
that the newly proposed method is promising in extrapolating the active
region or the whole sun magnetic fields in the solar atmosphere based
on the observed vector magnetic field on the photosphere.
---------------------------------------------------------
Title: An Explanation for Large Enhancements of Nitrogen relative
to Carbon and Oxygen in Solar <SUP>3</SUP>He-rich Events
Authors: Zhang, T. X.; Wang, J. X.
2003ApJ...588L..57Z Altcode:
Preferential heating and abundance enhancements of carbon (C),
nitrogen (N), and oxygen (O) in solar <SUP>3</SUP>He-rich energetic
particles are investigated in terms of the two-stage acceleration model
proposed by Zhang. It is shown that C<SUP>+5</SUP>, N<SUP>+6</SUP>,
and O<SUP>+7</SUP> are preferentially heated by H-cyclotron waves with a
frequency close to twice the <SUP>3</SUP>He-cyclotron frequency through
the third harmonic resonance. If the initial electron temperature of
the solar corona is in the range of ~2-3.2 MK, the abundance of N in
high-energy particles due to the second-stage acceleration is enhanced
by a factor of ~4-12 relative to C and O. The abundance pattern of C,
N, and O obtained from the two-stage acceleration model is consistent
with recent measurements (Mason, Mazur, & Dwyer). In addition,
harmonic resonances of neon, silicon, magnesium, sulfur, calcium,
and iron with the H-cyclotron waves are discussed.
---------------------------------------------------------
Title: No X-Ray-bright Type II Quasars among the Lyα Emitters
Authors: Malhotra, S.; Wang, J. X.; Rhoads, J. E.; Heckman, T. M.;
Norman, C. A.
2003ApJ...585L..25M Altcode: 2003astro.ph..1622M
The Lyα emitters found at z=4.5 and 5.7 by the Large Area Lyman Alpha
(LALA) survey have high equivalent widths in the Lyα line. Such lines
can be produced by narrow-lined active galactic nuclei or by stellar
populations with a very high proportion of young massive stars. To
check for type II (i.e., narrow-lined) quasars, we obtained a deep
X-ray image of 49 Lyα sources in a single field of the ACIS instrument
on the Chandra X-Ray Observatory. None of these sources was detected
with a 3 σ limiting X-ray luminosity of 2.9×10<SUP>43</SUP> ergs
s<SUP>-1</SUP>. For comparison, the two known high-redshift type II
quasars have luminosities of 4×10<SUP>43</SUP> ergs s<SUP>-1</SUP>
before extinction correction. The sources remain undetected in
stacked images of the 49 Lyα sources (with 6.5 Ms effective Chandra
on-axis exposure) at 3 σ limits of 4.9×10<SUP>42</SUP>. The resulting
X-ray-to-Lyα ratio is about 4-24 times lower than the ratio for known
type II quasars, while the average Lyα luminosity of the LALA sample
is between the two type II's. The cumulative X-ray-to-Lyα ratio limit
is also below that of 90% of low-redshift Seyfert galaxies.
---------------------------------------------------------
Title: Influence of turbulent magnetic fields on mode frequencies
Authors: Bi, S. L.; Liao, Y.; Wang, J. X.
2003A&A...397.1069B Altcode:
To investigate the physical nature of solar convective zone, we employ
the observed frequency shifts of solar oscillations to study the
influence of magnetic perturbation inside the Sun on the low-l solar
p-mode oscillations. We describe the various possibility of frequency
shifts for a time-dependent source of MHD turbulence. For the magnetic
perturbation contribution, we obtain the frequency shifts of modes with
different degree as a function of the spectrum of fluctuating magnetic
field. The frequency shift is found to increase with the strength of
magnetic fields in solar interior, and its temporal behavior closely
follows the phase of the synthetic solar activity cycle. Our analysis
indicates that the magnetic activities cause shifts of up to 0.3 muHz
. It is obviously shown that mode frequency, which is sensitive to
the effect of magnetic fields, can be used as a diagnostic tool for
the presence of turbulent magnetic fields in the convection zone.
---------------------------------------------------------
Title: Direct Evidence for Neutrino Flavor Transformation from
Neutral-Current Interactions in SNO
Authors: McDonald, A. B.; Ahmad, Q. R.; Allen, R. C.; Andersen, T. C.;
Anglin, J. D.; Barton, J. C.; Beier, E. W.; Bercovitch, M.; Bigu, J.;
Biller, S. D.; Black, R. A.; Blevis, I.; Boardman, R. J.; Boger, J.;
Bonvin, E.; Boulay, M. G.; Bowler, M. G.; Bowles, T. J.; Brice, S. J.;
Browne, M. C.; Bullard, T. V.; Bühler, G.; Cameron, J.; Chan, Y. D.;
Chen, H. H.; Chen, M.; Chen, X.; Cleveland, B. T.; Clifford, E. T. H.;
Cowan, J. H. M.; Cowen, D. F.; Cox, G. A.; Dai, X.; Dalnoki-Veress, F.;
Davidson, W. F.; Doe, P. J.; Doucas, G.; Dragowsky, M. R.; Duba, C. A.;
Duncan, F. A.; Dunford, M.; Dunmore, J. A.; Earle, E. D.; Elliott,
S. R.; Evans, H. C.; Ewan, G. T.; Farine, J.; Fergani, H.; Ferraris,
A. P.; Ford, R. J.; Formaggio, J. A.; Fowler, M. M.; Frame, K.; Frank,
E. D.; Frati, W.; Gagnon, N.; Germani, J. V.; Gil, S.; Graham, K.;
Grant, D. R.; Hahn, R. L.; Hallin, A. L.; Hallman, E. D.; Hamer,
A. S.; Hamian, A. A.; Handler, W. B.; Haq, R. U.; Hargrove, C. K.;
Harvey, P. J.; Hazama, R.; Heeger, K. M.; Heintzelman, W. J.; Heise,
J.; Helmer, R. L.; Hepburn, J. D.; Heron, H.; Hewett, J.; Hime, A.;
Howe, M.; Hykawy, J. G.; Isaac, M. C. P.; Jagam, P.; Jelley, N. A.;
Jillings, C.; Jonkmans, G.; Kazkaz, K.; Keener, P. T.; Klein, J. R.;
Knox, A. B.; Komar, R. J.; Kouzes, R.; Kutter, T.; Kyba, C. C. M.;
Law, J.; Lawson, I. T.; Lay, M.; Lee, H. W.; Lesko, K. T.; Leslie,
J. R.; Levine, I.; Locke, W.; Luoma, S.; Lyon, J.; Majerus, S.; Mak,
H. B.; Maneira, J.; Manor, J.; Marino, A. D.; McCauley, N.; McDonald,
D. S.; McFarlane, K.; McGregor, G.; Meijer Drees, R.; Mifflin, C.;
Miller, G. G.; Milton, G.; Moffat, B. A.; Moorhead, M.; Nally, C. W.;
Neubauer, M. S.; Newcomer, F. M.; Ng, H. S.; Noble, A. J.; Norman,
E. B.; Novikov, V. M.; O'Neill, M.; Okada, C. E.; Ollerhead, R. W.;
Omori, M.; Orrell, J. L.; Oser, S. M.; Poon, A. W. P.; Radcliffe,
T. J.; Roberge, A.; Robertson, B. C.; Robertson, R. G. H.; Rosendahl,
S. S. E.; Rowley, J. K.; Rusu, V. L.; Saettler, E.; Schaffer, K. K.;
Schwendener, M. H.; Schülke, A.; Seifert, H.; Shatkay, M.; Simpson,
J. J.; Sims, C. J.; Sinclair, D.; Skensved, P.; Smith, A. R.; Smith,
M. W. E.; Spreitzer, T.; Starinsky, N.; Steiger, T. D.; Stokstad,
R. G.; Stonehill, L. C.; Storey, R. S.; Sur, B.; Tafirout, R.; Tagg,
N.; Tanner, N. W.; Taplin, R. K.; Thorman, M.; Thornewell, P. M.;
Trent, P. T.; Tserkovnyak, Y. I.; van Berg, R.; van de Water, R. G.;
Virtue, C. J.; Waltham, C. E.; Wang, J. -X.; Wark, D. L.; West,
N.; Wilhelmy, J. B.; Wilkerson, J. F.; Wilson, J. R.; Wittich, P.;
Wouters, J. M.; Yeh, M.
2002AIPC..646...43M Altcode:
The Sudbury Neutrino Observatory (SNO) is a 1,000 tonne heavy
water Cerenkov-based neutrino detector situated 2,000 meters
underground in INCO's Creighton Mine near Sudbury, Ontario,
Canada. For the neutrinos from <SUP>8</SUP>B decay in the Sun SNO
observes the Charged Current neutrino reaction sensitive only
to electron neutrinos and others (Neutral Current and Elastic
Scattering) sensitive to all active neutrino types and thereby
can search for direct evidence of neutrino flavor change. Using
these reactions and assuming the standard <SUP>8</SUP>B shape, the
ve component of the <SUP>8</SUP>B solar flux is φe = 1.76<SUB>-
0.05</SUB><SUP>+0.05</SUP>(stat.)<SUB>- 0.09</SUB><SUP>+0.09</SUP>
(syst.) × 10<SUP>6</SUP> cm<SUP>-2</SUP>s<SUP>-1</SUP> for a kinetic
energy threshold of 5 MeV. The non-ve component is fgr μτ = 3.41<SUB>-
0.45</SUB><SUP>+0.45</SUP>(stat.)<SUB>- 0.45</SUB><SUP>+0.48</SUP>
(syst.) × 10<SUP>6</SUP> cm<SUP>-2</SUP>s<SUP>-1</SUP>, 5.3σ
greater than zero, providing strong evidence for solar ve flavor
transformation. The total flux measured with the NC reaction is
fgr NC = 5.09<SUB>- 0.43</SUB><SUP>+0.44</SUP>(stat.)<SUB>-
0.43</SUB><SUP>+0.46</SUP> (syst.) × 10<SUP>6</SUP>
cm<SUP>-2</SUP>s<SUP>-1</SUP>, consistent with solar models. For charged
current events, assuming an undistorted <SUP>8</SUP>B spectrum, the
night minus day rate is 14.0% +/- 6.3%<SUB>-1.4</SUB><SUP>+1.5</SUP>% of
the average rate. If the total flux of active neutrinos is additionally
constrained to have no asymmetry, the ve asymmetry is found to be
7.0% +/- 4.9%<SUB>-1.2</SUB><SUP>+1.3</SUP>%. A global solar neutrino
analysis in terms of matter-enhanced oscillations of two active flavors
strongly favors the Large Mixing Angle (LMA) solution.
---------------------------------------------------------
Title: A statistical study on the geoeffectiveness of Earth-directed
coronal mass ejections from March 1997 to December 2000
Authors: Wang, Y. M.; Ye, P. Z.; Wang, S.; Zhou, G. P.; Wang, J. X.
2002JGRA..107.1340W Altcode:
We have identified 132 Earth-directed coronal mass ejections
(CMEs) based on the observations of the Large Angle Spectroscopic
Coronagraph (LASCO) and Extreme Ultraviolet Imaging Telescope (EIT)
on board of Solar and Heliospheric Observatory (SOHO) from March
1997 to December 2000 and carried out a statistical study on their
geoeffectiveness. The following results are obtained: (1) Only 45%
of the total 132 Earth-directed halo CMEs caused geomagnetic storms
with Kp ≥ 5; (2) The initial sites of these geoeffective halo CMEs
are rather symmetrically distributed in the heliographic latitude
of the visible solar disc, while asymmetrical in longitude with the
majority located in the west side of the central meridian; (3) The
frontside halo CMEs accompanied with solar flares (identified from
GOES-8 satellite observations) seem to be more geoeffective; (4) Only a
weak correlation between the CME projected speed and the transit time
is revealed. However, for the severe geomagnetic storms (with Kp ≥
7), a significant correlation at the confidence level of 99% is found.
---------------------------------------------------------
Title: A method for the prediction of relative sunspot number for
the remainder of a progressing cycle with application to cycle 23
Authors: Li, K. J.; Zhan, L. S.; Wang, J. X.; Liu, X. H.; Yun, H. S.;
Xiong, S. Y.; Liang, H. F.; Zhao, H. Z.
2002A&A...392..301L Altcode:
In this paper, we investigate the prospect of using previously
occurring sunspot cycle signatures to determine future behavior in
an ongoing cycle, with specific application to cycle 23, the current
sunspot cycle. We find that the gross level of solar activity (i.e.,
the sum of the total number of sunspots over the course of a sunspot
cycle) associated with cycle 23, based on a comparison of its first
several years of activity against similar periods of preceding cycles,
is such that cycle 23 best compares to cycle 2. Compared to cycles
2 and 22, respectively, cycle 23 appears 1.08 times larger and 0.75
times as large. Because cycle 2 was of shorter period, we infer that
cycle 23 also might be of shorter length (period less than 11 years),
ending sometime in late 2006 or early 2007.
---------------------------------------------------------
Title: Direct Evidence for Neutrino Flavor Transformation from
Neutral-Current Interactions in the Sudbury Neutrino Observatory
Authors: Ahmad, Q. R.; Allen, R. C.; Andersen, T. C.; Anglin, J. D.;
Barton, J. C.; Beier, E. W.; Bercovitch, M.; Bigu, J.; Biller, S. D.;
Black, R. A.; Blevis, I.; Boardman, R. J.; Boger, J.; Bonvin, E.;
Boulay, M. G.; Bowler, M. G.; Bowles, T. J.; Brice, S. J.; Browne,
M. C.; Bullard, T. V.; Bühler, G.; Cameron, J.; Chan, Y. D.; Chen,
H. H.; Chen, M.; Chen, X.; Cleveland, B. T.; Clifford, E. T.; Cowan,
J. H.; Cowen, D. F.; Cox, G. A.; Dai, X.; Dalnoki-Veress, F.; Davidson,
W. F.; Doe, P. J.; Doucas, G.; Dragowsky, M. R.; Duba, C. A.; Duncan,
F. A.; Dunford, M.; Dunmore, J. A.; Earle, E. D.; Elliott, S. R.;
Evans, H. C.; Ewan, G. T.; Farine, J.; Fergani, H.; Ferraris, A. P.;
Ford, R. J.; Formaggio, J. A.; Fowler, M. M.; Frame, K.; Frank, E. D.;
Frati, W.; Gagnon, N.; Germani, J. V.; Gil, S.; Graham, K.; Grant,
D. R.; Hahn, R. L.; Hallin, A. L.; Hallman, E. D.; Hamer, A. S.;
Hamian, A. A.; Handler, W. B.; Haq, R. U.; Hargrove, C. K.; Harvey,
P. J.; Hazama, R.; Heeger, K. M.; Heintzelman, W. J.; Heise, J.;
Helmer, R. L.; Hepburn, J. D.; Heron, H.; Hewett, J.; Hime, A.; Howe,
M.; Hykawy, J. G.; Isaac, M. C.; Jagam, P.; Jelley, N. A.; Jillings,
C.; Jonkmans, G.; Kazkaz, K.; Keener, P. T.; Klein, J. R.; Knox, A. B.;
Komar, R. J.; Kouzes, R.; Kutter, T.; Kyba, C. C.; Law, J.; Lawson,
I. T.; Lay, M.; Lee, H. W.; Lesko, K. T.; Leslie, J. R.; Levine, I.;
Locke, W.; Luoma, S.; Lyon, J.; Majerus, S.; Mak, H. B.; Maneira, J.;
Manor, J.; Marino, A. D.; McCauley, N.; McDonald, A. B.; McDonald,
D. S.; McFarlane, K.; McGregor, G.; Meijer Drees, R.; Mifflin,
C.; Miller, G. G.; Milton, G.; Moffat, B. A.; Moorhead, M.; Nally,
C. W.; Neubauer, M. S.; Newcomer, F. M.; Ng, H. S.; Noble, A. J.;
Norman, E. B.; Novikov, V. M.; O'Neill, M.; Okada, C. E.; Ollerhead,
R. W.; Omori, M.; Orrell, J. L.; Oser, S. M.; Poon, A. W.; Radcliffe,
T. J.; Roberge, A.; Robertson, B. C.; Robertson, R. G.; Rosendahl,
S. S.; Rowley, J. K.; Rusu, V. L.; Saettler, E.; Schaffer, K. K.;
Schwendener, M. H.; Schülke, A.; Seifert, H.; Shatkay, M.; Simpson,
J. J.; Sims, C. J.; Sinclair, D.; Skensved, P.; Smith, A. R.; Smith,
M. W.; Spreitzer, T.; Starinsky, N.; Steiger, T. D.; Stokstad, R. G.;
Stonehill, L. C.; Storey, R. S.; Sur, B.; Tafirout, R.; Tagg, N.;
Tanner, N. W.; Taplin, R. K.; Thorman, M.; Thornewell, P. M.; Trent,
P. T.; Tserkovnyak, Y. I.; van Berg, R.; van de Water, R. G.; Virtue,
C. J.; Waltham, C. E.; Wang, J. -X.; Wark, D. L.; West, N.; Wilhelmy,
J. B.; Wilkerson, J. F.; Wilson, J. R.; Wittich, P.; Wouters, J. M.;
Yeh, M.
2002PhRvL..89a1301A Altcode: 2002nucl.ex...4008S; 2002nucl.ex...4008C
Observations of neutral-current ν interactions on deuterium in
the Sudbury Neutrino Observatory are reported. Using the neutral
current (NC), elastic scattering, and charged current reactions
and assuming the standard <SUP>8</SUP>B shape, the ν<SUB>e</SUB>
component of the <SUP>8</SUP>B solar flux is φ<SUB>e</SUB> =
1.76<SUP>+0.05</SUP><SUB>-0.05</SUB>(stat)<SUP>+0.09</SUP><SUB>-
0.09</SUB>(syst)×10<SUP>6</SUP> cm<SUP>-2</SUP>
s<SUP>-1</SUP> for a kinetic energy threshold of 5 MeV. The
non- ν<SUB>e</SUB> component is φ<SUB>μτ</SUB> =
3.41<SUP>+0.45</SUP><SUB>-0.45</SUB>(stat)<SUP>+0.48</SUP><SUB>-
0.45</SUB>(syst)×10<SUP>6</SUP> cm<SUP>-2</SUP>
s<SUP>-1</SUP>, 5.3σ greater than zero, providing strong
evidence for solar ν<SUB>e</SUB> flavor transformation. The
total flux measured with the NC reaction is φ<SUB>NC</SUB> =
5.09<SUP>+0.44</SUP><SUB>-0.43</SUB>(stat)<SUP>+0.46</SUP><SUB>-
0.43</SUB>(syst)×10<SUP>6</SUP> cm<SUP>-2</SUP> s<SUP>-1</SUP>,
consistent with solar models.
---------------------------------------------------------
Title: Measurement of Day and Night Neutrino Energy Spectra at SNO
and Constraints on Neutrino Mixing Parameters
Authors: Ahmad, Q. R.; Allen, R. C.; Andersen, T. C.; Anglin, J. D.;
Barton, J. C.; Beier, E. W.; Bercovitch, M.; Bigu, J.; Biller, S. D.;
Black, R. A.; Blevis, I.; Boardman, R. J.; Boger, J.; Bonvin, E.;
Boulay, M. G.; Bowler, M. G.; Bowles, T. J.; Brice, S. J.; Browne,
M. C.; Bullard, T. V.; Bühler, G.; Cameron, J.; Chan, Y. D.; Chen,
H. H.; Chen, M.; Chen, X.; Cleveland, B. T.; Clifford, E. T.; Cowan,
J. H.; Cowen, D. F.; Cox, G. A.; Dai, X.; Dalnoki-Veress, F.; Davidson,
W. F.; Doe, P. J.; Doucas, G.; Dragowsky, M. R.; Duba, C. A.; Duncan,
F. A.; Dunford, M.; Dunmore, J. A.; Earle, E. D.; Elliott, S. R.;
Evans, H. C.; Ewan, G. T.; Farine, J.; Fergani, H.; Ferraris, A. P.;
Ford, R. J.; Formaggio, J. A.; Fowler, M. M.; Frame, K.; Frank, E. D.;
Frati, W.; Gagnon, N.; Germani, J. V.; Gil, S.; Graham, K.; Grant,
D. R.; Hahn, R. L.; Hallin, A. L.; Hallman, E. D.; Hamer, A. S.;
Hamian, A. A.; Handler, W. B.; Haq, R. U.; Hargrove, C. K.; Harvey,
P. J.; Hazama, R.; Heeger, K. M.; Heintzelman, W. J.; Heise, J.;
Helmer, R. L.; Hepburn, J. D.; Heron, H.; Hewett, J.; Hime, A.; Howe,
M.; Hykawy, J. G.; Isaac, M. C.; Jagam, P.; Jelley, N. A.; Jillings,
C.; Jonkmans, G.; Kazkaz, K.; Keener, P. T.; Klein, J. R.; Knox, A. B.;
Komar, R. J.; Kouzes, R.; Kutter, T.; Kyba, C. C.; Law, J.; Lawson,
I. T.; Lay, M.; Lee, H. W.; Lesko, K. T.; Leslie, J. R.; Levine, I.;
Locke, W.; Luoma, S.; Lyon, J.; Majerus, S.; Mak, H. B.; Maneira, J.;
Manor, J.; Marino, A. D.; McCauley, N.; McDonald, A. B.; McDonald,
D. S.; McFarlane, K.; McGregor, G.; Meijer Drees, R.; Mifflin,
C.; Miller, G. G.; Milton, G.; Moffat, B. A.; Moorhead, M.; Nally,
C. W.; Neubauer, M. S.; Newcomer, F. M.; Ng, H. S.; Noble, A. J.;
Norman, E. B.; Novikov, V. M.; O'Neill, M.; Okada, C. E.; Ollerhead,
R. W.; Omori, M.; Orrell, J. L.; Oser, S. M.; Poon, A. W.; Radcliffe,
T. J.; Roberge, A.; Robertson, B. C.; Robertson, R. G.; Rosendahl,
S. S.; Rowley, J. K.; Rusu, V. L.; Saettler, E.; Schaffer, K. K.;
Schwendener, M. H.; Schülke, A.; Seifert, H.; Shatkay, M.; Simpson,
J. J.; Sims, C. J.; Sinclair, D.; Skensved, P.; Smith, A. R.; Smith,
M. W.; Spreitzer, T.; Starinsky, N.; Steiger, T. D.; Stokstad, R. G.;
Stonehill, L. C.; Storey, R. S.; Sur, B.; Tafirout, R.; Tagg, N.;
Tanner, N. W.; Taplin, R. K.; Thorman, M.; Thornewell, P. M.; Trent,
P. T.; Tserkovnyak, Y. I.; van Berg, R.; van de Water, R. G.; Virtue,
C. J.; Waltham, C. E.; Wang, J. -X.; Wark, D. L.; West, N.; Wilhelmy,
J. B.; Wilkerson, J. F.; Wilson, J. R.; Wittich, P.; Wouters, J. M.;
Yeh, M.
2002PhRvL..89a1302A Altcode: 2002nucl.ex...4009S; 2002nucl.ex...4009C
The Sudbury Neutrino Observatory (SNO) has measured day and night
solar neutrino energy spectra and rates. For charged current events,
assuming an undistorted <SUP>8</SUP>B spectrum, the night minus day
rate is 14.0%+/-6.3%<SUP>+1.5</SUP><SUB>-1.4</SUB>% of the average
rate. If the total flux of active neutrinos is additionally constrained
to have no asymmetry, the ν<SUB>e</SUB> asymmetry is found to be
7.0%+/-4.9%<SUP>+1.3</SUP><SUB>-1.2</SUB>%. A global solar neutrino
analysis in terms of matter-enhanced oscillations of two active flavors
strongly favors the large mixing angle solution.
---------------------------------------------------------
Title: Magnetic Field Strengths and Structures from Radio Observations
of Solar Active Regions
Authors: Zhang, Chang-Xi; Gelfreikh, G. B.; Wang, Jing-Xiu
2002ChJAA...2..266Z Altcode:
Radio observations of some active regions (ARs) obtained with the
Nobeyama radioheliograph at λ=1.76 cm are used for estimating the
magnetic field strength in the upper chromosphere, based on thermal
bremsstrahlung. The results are compared with the magnetic field
strength in the photosphere from observations with the Solar Magnetic
Field Telescope (SMFT) at Huairou Solar Observing Station of Beijing
Astronomical Observatory. The difference in the magnetic field strength
between the two layers seems reasonable. The solar radio maps of active
regions obtained with the Nobeyama radioheliograph, both in total
intensity (I-map) and in circular polarizations (V-map), are compared
with the optical magnetograms obtained with the SMFT. The comparison
between the radio map in circular polarization and the longitudinal
photospheric magnetogram of a plage region suggests that the radio
map in circular polarization is a kind of magnetogram of the upper
chromosphere. The comparison of the radio map in total intensity with
the photospheric vector magnetogram of an AR shows that the radio map
in total intensity gives indications of magnetic loops in the corona,
thus we have a method of defining the coronal magnetic structure from
the radio I-maps at λ=1.76 cm. Analysing the I-maps, we identified
three components: (a) a compact bright source; (b) a narrow elongated
structure connecting two main magnetic islands of opposite polarities
(observed in both the optical and radio magnetograms); (c) a wide,
diffuse, weak component that corresponds to a wide structure in the
solar active region which shows in most cases an S or a reversed
S contour, which is probably due to the differential rotation of
the Sun. The last two components suggest coronal loops on different
spatial scales above the neutral line of the longitudinal photospheric
magnetic field.
---------------------------------------------------------
Title: Regularity of the north-south asymmetry of solar activity
Authors: Li, K. J.; Wang, J. X.; Xiong, S. Y.; Liang, H. F.; Yun,
H. S.; Gu, X. M.
2002A&A...383..648L Altcode:
In the present work, the dominant hemisphere of solar activity in each
of solar cycles 12 to 22 has been clarified by calculating the actual
probability of the hemispheric distribution of several solar activity
phenomena using long-term observational records. An attempt is made
to demonstrate that a long characteristic time scale, about 12-cycle
length, is inferred to occur in solar activity.
---------------------------------------------------------
Title: Can Asymmetry of Solar Activity be Extended into Extended
Cycle?
Authors: Li, Ke-Jun; Wang, Jing-Xiu; Liang, Hong-Fei; Gu, Xiao-Ma
2002ChJAA...2...66L Altcode:
With the use of the Royal Greenwich Observatory data set of sunspot
groups, an attempt is made to examine the north-south asymmetry of
solar activity in the “extended” solar cycles. It is inferred that
the asymmetry established for individual solar cycles does not extend
to the "extended" cycles.
---------------------------------------------------------
Title: The Chandra Deep Field-South: The 1 Million Second Exposure
Authors: Rosati, P.; Tozzi, P.; Giacconi, R.; Gilli, R.; Hasinger, G.;
Kewley, L.; Mainieri, V.; Nonino, M.; Norman, C.; Szokoly, G.; Wang,
J. X.; Zirm, A.; Bergeron, J.; Borgani, S.; Gilmozzi, R.; Grogin,
N.; Koekemoer, A.; Schreier, E.; Zheng, W.
2002ApJ...566..667R Altcode:
We present the main results from our 940 ks observation of the Chandra
Deep Field-South using the source catalog described in an accompanying
paper by Giacconi et al. We extend the measurement of source number
counts to 5.5×10<SUP>-17</SUP> ergs cm<SUP>-2</SUP> s<SUP>-1</SUP> in
the soft 0.5-2 keV band and 4.5×10<SUP>-16</SUP> ergs cm<SUP>-2</SUP>
s<SUP>-1</SUP> in the hard 2-10 keV band. The hard-band logN-logS
shows a significant flattening (slope ~=0.6) below ~10<SUP>-14</SUP>
ergs cm<SUP>-2</SUP> s<SUP>-1</SUP>, leaving at most 10%-15% of the
X-ray background to be resolved, the main uncertainty lying in the
measurement of the total flux of the X-ray background (XRB). On the
other hand, the analysis in the very hard 5-10 keV band reveals a
relatively steep logN-logS (slope ~=1.3) down to 10<SUP>-15</SUP>
ergs cm<SUP>-2</SUP> s<SUP>-1</SUP>. Together with the evidence of
a progressive flattening of the average X-ray spectrum near the flux
limit, this indicates that there is still a nonnegligible population
of faint hard sources to be discovered at energies not well probed
by Chandra, which possibly contributes to the 30 keV bump in the
spectrum of the XRB. We use optical redshifts and identifications,
obtained with the Very Large Telescope, for one-quarter of the sample to
characterize the combined optical and X-ray properties of the Chandra
Deep Field-South sample. Different source types are well separated
in a parameter space that includes X-ray luminosity, hardness ratio,
and R-K color. Type II objects, while redder on average than the
field population, have colors that are consistent with being hosted
by a range of galaxy types. Type II active galactic nuclei are mostly
found at z<~1, in contrast with predictions based on active galactic
nucleus population synthesis models, thus suggesting a revision of their
evolutionary parameters. Based on observations made at the European
Southern Observatory (ESO), the Paranal Observatory Office, Antofagasta,
Chile. The ESO Imaging Survey observations have been carried out using
the ESO New Technology Telescope (NTT) at the La Silla Observatory,
Avenida, El Santo 1538, La Serena, Chile (ESO LP 164.O-O561).
---------------------------------------------------------
Title: What Can We Learn From Constructing CME Models
Authors: Lin, J.; Wang, J. X.
2002stma.conf..137L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic Flux Cancellation Associated with Coronal Mass
Ejections
Authors: Wang, J. X.; Zhang, J.; Deng, Y. Y.
2002stma.conf...93W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: New Results from the X-Ray and Optical Survey of the Chandra
Deep Field-South: The 300 Kilosecond Exposure. II.
Authors: Tozzi, P.; Rosati, P.; Nonino, M.; Bergeron, J.; Borgani,
S.; Gilli, R.; Gilmozzi, R.; Hasinger, G.; Grogin, N.; Kewley, L.;
Koekemoer, A.; Norman, C.; Schreier, E.; Szokoly, G.; Wang, J. X.;
Zheng, W.; Zirm, A.; Giacconi, R.
2001ApJ...562...42T Altcode: 2001astro.ph..3014T
We present results from 300 ks of X-ray observations of the Chandra
Deep Field-South. The field of the four combined exposures is now
0.1035 deg<SUP>2</SUP>, and we reach a flux limit of 10<SUP>-16</SUP>
ergs s<SUP>-1</SUP> cm<SUP>-2</SUP> in the 0.5-2 keV soft band and
10<SUP>-15</SUP> ergs s<SUP>-1</SUP> cm<SUP>-2</SUP> in the 2-10
keV hard band, i.e., a factor of 2 fainter than the previous 120
ks exposure. The total catalog is composed of 197 sources including
22 sources detected only in the hard band, 51 only in the soft band,
and 124 detected in both bands. We now have the optical spectra for 86
optical counterparts. The logN-logS relationship of the whole sample
confirms the flattening with respect to the ASCA hard counts and the
ROSAT soft counts. The average logarithmic slopes of the number counts
are α=0.66+/-0.06 and α=0.92+/-0.12 in the soft and hard bands,
respectively. Double power-law fits to the differential counts show
evidence of further flattening at the very faint end to slopes of
0.5+/-0.1 and 0.6+/-0.2 in the soft and hard bands, respectively. We
compute the total contribution to the X-ray background (XRB) in the
2-10 keV band, which now amounts to (1.45+/-0.15)×10<SUP>-11</SUP> ergs
cm<SUP>-2</SUP> s<SUP>-1</SUP> deg<SUP>-2</SUP> (after the inclusion of
the ASCA sources to account for the bright end) to a lower flux limit of
10<SUP>-15</SUP> ergs s<SUP>-1</SUP> cm<SUP>-2</SUP>. This corresponds
to 60%-90% of the unresolved hard XRB, given the uncertainties
on its actual value. We confirm previous findings on the average
spectrum of the sources, which is well described by a power law
with Γ=1.44+/-0.03, and the progressive hardening of the sources at
lower fluxes. In particular, we find that the average spectral slope
of the sources is flatter than the average for fluxes lower than
9×10<SUP>-15</SUP> ergs s<SUP>-1</SUP> cm<SUP>-2</SUP> in the hard
band. The hardening of the spectra is consistent with an increasing
fraction of absorbed objects (N<SUB>H</SUB>>10<SUP>22</SUP>
cm<SUP>-2</SUP>) at low fluxes. From 86 redshifts available at present,
we find that hard sources have on average lower redshifts (z<=1)
than soft sources. Their typical luminosities and optical spectra
show that most of these sources are obscured active galactic nuclei
(AGNs), as expected by AGN population synthesis models of the XRB. We
are still in the process of finding hard sources that constitute the
remaining fraction of the total XRB. Most of the sources detected
only in the soft band appear to be optically normal galaxies with
luminosities L<SUB>X</SUB>~=10<SUP>40</SUP>-10<SUP>42</SUP> ergs
s<SUP>-1</SUP>. This population appears to be a mix of normal galaxies,
possibly with enhanced star formation, and galaxies with low-level
nuclear activity. Based on observations performed at the European
Southern Observatory, Paranal, Chile.
---------------------------------------------------------
Title: Ultraviolet Broad Absorption Features and the Spectral Energy
Distribution of the Quasar PG 1351+64
Authors: Zheng, W.; Kriss, G. A.; Wang, J. X.; Brotherton, M.; Oegerle,
W. R.; Blair, W. P.; Davidsen, A. F.; Green, R. F.; Hutchings, J. B.;
Kaiser, M. E.
2001ApJ...562..152Z Altcode: 2001astro.ph..7536Z
We present a moderate-resolution (~20 km s<SUP>-1</SUP>) spectrum of
the mini-broad absorption line quasar (QSO) PG 1351+64 between 915
and 1180 Å, obtained with the Far Ultraviolet Spectroscopic Explorer
(FUSE). Additional low-resolution spectra at longer wavelengths were
also obtained with the Hubble Space Telescope (HST) and ground-based
telescopes. Broad absorption is present on the blue wings of C III
λ977, Lyβ, O VI λλ1032, 1038, Lyα, N V λλ1238, 1242, Si IV
λλ1393, 1402, and C IV λλ1548, 1550. The absorption profile can be
fitted with five components at velocities of ~-780, -1049, -1629, -1833,
and -3054 km s<SUP>-1</SUP> with respect to the emission-line redshift
of z=0.088. All the absorption components cover a large fraction of the
continuum source, as well as the broad-line region. The O VI emission
feature is very weak, and the O VI/Lyα flux ratio is 0.08, one of the
lowest among low-redshift active galaxies and QSOs. The UV continuum
shows a significant change in slope near 1050 Å in the rest frame. The
steeper continuum shortward of the Lyman limit extrapolates well to the
observed weak X-ray flux level. The absorbers' properties are similar
to those of high-redshift broad absorption line QSOs. The derived total
column density of the UV absorbers is on the order of 10<SUP>21</SUP>
cm<SUP>-2</SUP>, unlikely to produce significant opacity above 1
keV in the X-ray. Unless there is a separate, high-ionization X-ray
absorber, the QSO's weak X-ray flux may be intrinsic. The ionization
level of the absorbing components is comparable to that anticipated
in the broad-line region; therefore, the absorbers may be related
to broad-line clouds along the line of sight. Based on observations
made for the Guaranteed Time Team by the NASA-CNES-CSA FUSE mission,
operated by the Johns Hopkins University under NASA contract NAS
5-32985, and observations with the NASA/ESA Hubble Space Telescope,
obtained at the Space Telescope Science Institute, which is operated
by the Association of Universities of Research in Astronomy, Inc.,
under NASA contract NAS 5-26555.
---------------------------------------------------------
Title: The Chandra Deep Field South: the 1 Million Second
Authors: Rosati, P.; Tozzi, P.; Giacconi, R.; Gilli, R.; Hasinger, G.;
Kewley, L.; Mainieri, V.; Nonino, M.; Norman, C.; Szokoly, G.; Wang,
J. X.; Zirm, A.; Bergeron, J.; Borgani, S.; Gilmozzi, R.; Grogin,
N.; Koekemoer, A.; Schreier, E.; Zheng, W.
2001astro.ph.10452R Altcode:
We present the main results from our 940 ksec observation of the Chandra
Deep Field South (CDFS), using the source catalog described in an
accompanying paper (Giacconi et al. 2001). We extend the measurement
of source number counts to 5.5e-17 erg/cm^2/s in the soft 0.5-2 keV
band and 4.5e-16 erg/cm^2/s in the hard 2-10 keV band. The hard band
LogN-LogS shows a significant flattening (slope~=0.6) below ~1e-14
erg/cm^2/s, leaving at most 10-15% of the X-ray background (XRB)
to be resolved, the main uncertainty lying in the measurement of the
total flux of the XRB. On the other hand, the analysis in the very
hard 5-10 keV band reveals a relatively steep LogN-LogS (slope ~=1.3)
down to 1e-15 erg/cm^2/s. Together with the evidence of a progressive
flattening of the average X-ray spectrum near the flux limit, this
indicates that there is still a non negligible population of faint
hard sources to be discovered at energies not well probed by Chandra,
which possibly contribute to the 30 keV bump in the spectrum of the
XRB. We use optical redshifts and identifications, obtained with the
VLT, for one quarter of the sample to characterize the combined optical
and X-ray properties of the CDFS sample. Different source types are well
separated in a parameter space which includes X-ray luminosity, hardness
ratio and R-K color. Type II objects, while redder on average than the
field population, have colors which are consistent with being hosted
by a range of galaxy types. Type II AGN are mostly found at z<~1,
in contrast with predictions based on AGN population synthesis models,
thus suggesting a revision of their evolutionary parameters.
---------------------------------------------------------
Title: Measurement of the Rate of ν<SUB>e</SUB> + d --> p + p +
e<SUP>-</SUP> Interactions Produced by <SUP>8</SUP>B Solar Neutrinos
at the Sudbury Neutrino Observatory
Authors: Ahmad, Q. R.; Allen, R. C.; Andersen, T. C.; Anglin, J. D.;
Bühler, G.; Barton, J. C.; Beier, E. W.; Bercovitch, M.; Bigu,
J.; Biller, S.; Black, R. A.; Blevis, I.; Boardman, R. J.; Boger,
J.; Bonvin, E.; Boulay, M. G.; Bowler, M. G.; Bowles, T. J.; Brice,
S. J.; Browne, M. C.; Bullard, T. V.; Burritt, T. H.; Cameron, K.;
Cameron, J.; Chan, Y. D.; Chen, M.; Chen, H. H.; Chen, X.; Chon,
M. C.; Cleveland, B. T.; Clifford, E. T.; Cowan, J. H.; Cowen,
D. F.; Cox, G. A.; Dai, Y.; Dai, X.; Dalnoki-Veress, F.; Davidson,
W. F.; Doe, P. J.; Doucas, G.; Dragowsky, M. R.; Duba, C. A.; Duncan,
F. A.; Dunmore, J.; Earle, E. D.; Elliott, S. R.; Evans, H. C.; Ewan,
G. T.; Farine, J.; Fergani, H.; Ferraris, A. P.; Ford, R. J.; Fowler,
M. M.; Frame, K.; Frank, E. D.; Frati, W.; Germani, J. V.; Gil, S.;
Goldschmidt, A.; Grant, D. R.; Hahn, R. L.; Hallin, A. L.; Hallman,
E. D.; Hamer, A.; Hamian, A. A.; Haq, R. U.; Hargrove, C. K.; Harvey,
P. J.; Hazama, R.; Heaton, R.; Heeger, K. M.; Heintzelman, W. J.;
Heise, J.; Helmer, R. L.; Hepburn, J. D.; Heron, H.; Hewett, J.;
Hime, A.; Howe, M.; Hykawy, J. G.; Isaac, M. C.; Jagam, P.; Jelley,
N. A.; Jillings, C.; Jonkmans, G.; Karn, J.; Keener, P. T.; Kirch,
K.; Klein, J. R.; Knox, A. B.; Komar, R. J.; Kouzes, R.; Kutter, T.;
Kyba, C. C.; Law, J.; Lawson, I. T.; Lay, M.; Lee, H. W.; Lesko, K. T.;
Leslie, J. R.; Levine, I.; Locke, W.; Lowry, M. M.; Luoma, S.; Lyon,
J.; Majerus, S.; Mak, H. B.; Marino, A. D.; McCauley, N.; McDonald,
A. B.; McDonald, D. S.; McFarlane, K.; McGregor, G.; McLatchie, W.;
Drees, R. Meijer; Mes, H.; Mifflin, C.; Miller, G. G.; Milton, G.;
Moffat, B. A.; Moorhead, M.; Nally, C. W.; Neubauer, M. S.; Newcomer,
F. M.; Ng, H. S.; Noble, A. J.; Norman, E. B.; Novikov, V. M.; O'Neill,
M.; Okada, C. E.; Ollerhead, R. W.; Omori, M.; Orrell, J. L.; Oser,
S. M.; Poon, A. W.; Radcliffe, T. J.; Roberge, A.; Robertson, B. C.;
Robertson, R. G.; Rowley, J. K.; Rusu, V. L.; Saettler, E.; Schaffer,
K. K.; Schuelke, A.; Schwendener, M. H.; Seifert, H.; Shatkay, M.;
Simpson, J. J.; Sinclair, D.; Skensved, P.; Smith, A. R.; Smith, M. W.;
Starinsky, N.; Steiger, T. D.; Stokstad, R. G.; Storey, R. S.; Sur,
B.; Tafirout, R.; Tagg, N.; Tanner, N. W.; Taplin, R. K.; Thorman,
M.; Thornewell, P.; Trent, P. T.; Tserkovnyak, Y. I.; van Berg, R.;
van de Water, R. G.; Virtue, C. J.; Waltham, C. E.; Wang, J. -X.;
Wark, D. L.; West, N.; Wilhelmy, J. B.; Wilkerson, J. F.; Wilson,
J.; Wittich, P.; Wouters, J. M.; Yeh, M.
2001PhRvL..87g1301A Altcode: 2001nucl.ex...6015S; 2001nucl.ex...6015C
Solar neutrinos from <SUP>8</SUP>B decay have been detected
at the Sudbury Neutrino Observatory via the charged current
(CC) reaction on deuterium and the elastic scattering (ES) of
electrons. The flux of ν<SUB>e</SUB>'s is measured by the
CC reaction rate to be φ<SUP>CC</SUP>(ν<SUB>e</SUB>)
= 1.75+/-0.07(stat)<SUP>+0.12</SUP><SUB>-
0.11</SUB>(syst)+/-0.05(theor)×10<SUP>6</SUP> cm<SUP>-2</SUP>
s<SUP>-1</SUP>. Comparison of φ<SUP>CC</SUP>(ν<SUB>e</SUB>) to
the Super-Kamiokande Collaboration's precision value of the flux
inferred from the ES reaction yields a 3.3σ difference, assuming the
systematic uncertainties are normally distributed, providing evidence
of an active non- ν<SUB>e</SUB> component in the solar flux. The
total flux of active <SUP>8</SUP>B neutrinos is determined to be
5.44+/-0.99×10<SUP>6</SUP> cm<SUP>-2</SUP> s<SUP>-1</SUP>.
---------------------------------------------------------
Title: Resolving the X-ray background with Chandra: the 1 MS
observation of the Chandra Deep Field South *
Authors: Tozzi, P.; Bergeron, J.; Borgani, S.; Giacconi, R.; Gilli,
R.; Gilmozzi, R.; Grogin, N.; Hasinger, G.; Kellerman, K.; Kewley,
L.; Koekemoer, A.; Mainier, V.; Nonino, M.; Norman, C.; Rosati, P.;
Schreier, E.; Shaver, P.; Szokoly, G.; Wang, J. X.; Zheng, W.; Zirm, A.
2001cghr.confE..66T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Chandra Deep Field South
Authors: Giacconi, R.; Rosati, P.; Tozzi, P.; Borgani, S.; Hasinger,
G.; Bergeron, J.; Gilmozzi, R.; Nonino, M.; Gilli, R.; Zirm, A.;
Wang, J. X.; Zheng, W.; Kellermann, K. I.; Shaver, P.; Schreier, E.;
Koekemoer, A.; Grogin, N.; Norman, C.
2000AAS...197.9001G Altcode: 2000BAAS...32.1562G
We present results from the on-going ultra deep Chandra observations
in the Chandra Deep Field South (CDF-S). As of October 2000, we
have collected an exposure of 300 ksec which covers an area of 0.1
deg<SUP>2</SUP>. These new data confirm and strengthen some of the
conclusions of our initial analysis based on 130ksec observations
(Giacconi et al. 2000). At the current depth, the source surface density
is 3000/deg<SUP>2</SUP>. Number counts in the hard band (2-10keV)
have overtaken the soft (0.5-2) counts and show evidence of flattening
below 10<SUP>-15</SUP> erg/cm<SUP>2</SUP>/s [2-10 keV]. The hardening
of the source spectra continues to fainter fluxes, most likely the
result of an increasing absorption column. We discuss the implications
of these observations in light of new population synthesis models. We
will also show the spectro-photometric and morphological properties
of the optical counterparts from the on-going source identification
program with the VLT and HST/WFPC2. We acknowledge support from NASA
grants NAG-8-1527 and NAG-8-1133.
---------------------------------------------------------
Title: The X-Ray Absorber in Broad Absorption Line Quasars
Authors: Wang, T. G.; Brinkmann, W.; Yuan, W.; Wang, J. X.; Zhou, Y. Y.
2000ApJ...545...77W Altcode: 2000astro.ph..8291W
Recent observations of Broad Absorption Line (BAL) quasars demonstrated
that the soft X-ray emission of these objects is extremely weak, and
convincing evidence for very strong absorption by a high column density
(~10<SUP>23.5</SUP> cm<SUP>-2</SUP>) was obtained for PG 1411+442,
even though it is one of the few BAL QSOs strongly detected in soft
X-rays. This paper examines the ionization status and geometry of
the X-ray absorber by combining the properties of the UV lines with
the X-ray continuum absorption. We show that the gas has to have
large column densities in ions of major UV absorption lines, such
as C IV, N V, O VI, and Ne VIII, in order to have sufficient opacity
around 0.2-0.35 keV. The UV absorption lines have to be saturated if
the X-ray absorber intersects the line of sight to the UV continuum
emission region. A uniformly covering UV and X-ray absorption model can
be constructed for PG 1411+442, but in some other soft X-ray-detected
BAL QSOs, such as PG 1001+054, the observed line optical depth is much
lower than expected from the X-ray-absorbing material. We propose a
scheme in which a substantial fraction of the line of sight to the
continuum source may be covered by either an optically thick flow or
clouds in a narrow velocity range, but in which the total covering
factor of either the whole flow or all clouds is close to unity. The
absorber can contribute significantly to the extremely highly ionized
emission lines, such as O VI λλ1032/1037 and Ne VIII λλ770/780,
if it covers a substantial fraction of solid angle and if the density
is higher than 10<SUP>8</SUP> cm<SUP>-3</SUP>. However, it has very
little impact on the medium- and low-ionization UV lines such as N V
and C IV. The profiles of Ne VIII and O VI lines may be indicators for
the kinematics of the X-ray absorber in QSOs. The observed Ne VIII line
profiles in QSOs suggest that the velocity of the gas projected onto our
line of sight is similar to that seen in the outflows of the UV BALs.
---------------------------------------------------------
Title: The Sudbury Neutrino Observatory
Authors: Boger, J.; Hahn, R. L.; Rowley, J. K.; Carter, A. L.;
Hollebone, B.; Kessler, D.; Blevis, I.; Dalnoki-Veress, F.; DeKok,
A.; Farine, J.; Grant, D. R.; Hargrove, C. K.; Laberge, G.; Levine,
I.; McFarlane, K.; Mes, H.; Noble, A. T.; Novikov, V. M.; O'Neill,
M.; Shatkay, M.; Shewchuk, C.; Sinclair, D.; Clifford, E. T. H.; Deal,
R.; Earle, E. D.; Gaudette, E.; Milton, G.; Sur, B.; Bigu, J.; Cowan,
J. H. M.; Cluff, D. L.; Hallman, E. D.; Haq, R. U.; Hewett, J.; Hykawy,
J. G.; Jonkmans, G.; Michaud, R.; Roberge, A.; Roberts, J.; Saettler,
E.; Schwendener, M. H.; Seifert, H.; Sweezey, D.; Tafirout, R.;
Virtue, C. J.; Beck, D. N.; Chan, Y. D.; Chen, X.; Dragowsky, M. R.;
Dycus, F. W.; Gonzalez, J.; Isaac, M. C. P.; Kajiyama, Y.; Koehler,
G. W.; Lesko, K. T.; Moebus, M. C.; Norman, E. B.; Okada, C. E.; Poon,
A. W. P.; Purgalis, P.; Schuelke, A.; Smith, A. R.; Stokstad, R. G.;
Turner, S.; Zlimen, I.; Anaya, J. M.; Bowles, T. J.; Brice, S. J.;
Esch, E. -I.; Fowler, M. M.; Goldschmidt, A.; Hime, A.; McGirt,
A. F.; Miller, G. G.; Teasdale, W. A.; Wilhelmy, J. B.; Wouters,
J. M.; Anglin, J. D.; Bercovitch, M.; Davidson, W. F.; Storey, R. S.;
Biller, S.; Black, R. A.; Boardman, R. J.; Bowler, M. G.; Cameron, J.;
Cleveland, B.; Ferraris, A. P.; Doucas, G.; Heron, H.; Howard, C.;
Jelley, N. A.; Knox, A. B.; Lay, M.; Locke, W.; Lyon, J.; Majerus,
S.; Moorhead, M.; Omori, M.; Tanner, N. W.; Taplin, R. K.; Thorman,
M.; Wark, D. L.; West, N.; Barton, J. C.; Trent, P. T.; Kouzes, R.;
Lowry, M. M.; Bell, A. L.; Bonvin, E.; Boulay, M.; Dayon, M.; Duncan,
F.; Erhardt, L. S.; Evans, H. C.; Ewan, G. T.; Ford, R.; Hallin, A.;
Hamer, A.; Hart, P. M.; Harvey, P. J.; Haslip, D.; Hearns, C. A. W.;
Heaton, R.; Hepburn, J. D.; Jillings, C. J.; Korpach, E. P.; Lee,
H. W.; Leslie, J. R.; Liu, M. -Q.; Mak, H. B.; McDonald, A. B.;
MacArthur, J. D.; McLatchie, W.; Moffat, B. A.; Noel, S.; Radcliffe,
T. J.; Robertson, B. C.; Skensved, P.; Stevenson, R. L.; Zhu, X.; Gil,
S.; Heise, J.; Helmer, R. L.; Komar, R. J.; Nally, C. W.; Ng, H. S.;
Waltham, C. E.; Allen, R. C.; Bühler, G.; Chen, H. H.; Aardsma, G.;
Andersen, T.; Cameron, K.; Chon, M. C.; Hanson, R. H.; Jagam, P.; Karn,
J.; Law, J.; Ollerhead, R. W.; Simpson, J. J.; Tagg, N.; Wang, J. -X.;
Alexander, C.; Beier, E. W.; Cook, J. C.; Cowen, D. F.; Frank, E. D.;
Frati, W.; Keener, P. T.; Klein, J. R.; Mayers, G.; McDonald, D. S.;
Neubauer, M. S.; Newcomer, F. M.; Pearce, R. J.; de Water, R. G. V.;
Berg, R. V.; Wittich, P.; Ahmad, Q. R.; Beck, J. M.; Browne, M. C.;
Burritt, T. H.; Doe, P. J.; Duba, C. A.; Elliott, S. R.; Franklin,
J. E.; Germani, J. V.; Green, P.; Hamian, A. A.; Heeger, K. M.; Howe,
M.; Drees, R. M.; Myers, A.; Robertson, R. G. H.; Smith, M. W. E.;
Steiger, T. D.; Wechel, T. V.; Wilkerson, J. F.
2000NIMPA.449..172B Altcode: 1999nucl.ex..10016C; 1999nucl.ex..10016T
The Sudbury Neutrino Observatory is a second-generation water Cherenkov
detector designed to determine whether the currently observed
solar neutrino deficit is a result of neutrino oscillations. The
detector is unique in its use of D<SUB>2</SUB>O as a detection medium,
permitting it to make a solar model-independent test of the neutrino
oscillation hypothesis by comparison of the charged- and neutral-current
interaction rates. In this paper the physical properties, construction,
and preliminary operation of the Sudbury Neutrino Observatory are
described. Data and predicted operating parameters are provided
whenever possible.
---------------------------------------------------------
Title: X-Ray and Ultraviolet Spectral Properties of the X-Ray
Transient Quasar PG 0844+349
Authors: Wang, T. G.; Brinkmann, W.; Matsuoka, M.; Wang, J. X.;
Yuan, W.
2000ApJ...533..113W Altcode:
Despite the fact that quasars are generally strong X-ray emitters,
ROSAT discovered several objects with only very weak X-ray emission. In
this paper, the X-ray data from ASCA and ROSAT and the UV spectra
from Hubble Space Telescope (HST) and IUE of one of these quasars,
PG 0844+349, are analyzed. The ROSAT spectrum can be well fitted by a
single power law with Galactic absorption. No spectral variations were
observed during changes of the 0.1-2.4 keV X-ray flux by a factor of 10
between the ROSAT All-Sky Survey and pointed observations, separated
by 6 months. The ASCA satellite found the object in a high state with
a photon index of 1.98 and an Fe Kα line with EW~300 eV. The X-ray
flux in the 2-10 keV band is highly variable; the fastest variation
detected is 60% in less than 2×10<SUP>4</SUP> s. The measured excess
variance fits well the excess variance versus L<SUB>2-10keV</SUB>
relation for Seyfert 1 galaxies; the flux variability in the 0.5-2.0 keV
band shows a slightly higher amplitude than in the 2-10 keV band. We
show that the optical microvariability of this object can actually be
driven by reprocessing of the variable X-ray flux if one-half of the
absorbed X-rays are reradiated in the optical-to-UV band. A weak broad
intrinsic absorption line (FWHM~=800 km s<SUP>-1</SUP>), most likely
Lyα absorption blueshifted by a velocity ~=-6000 km s<SUP>-1</SUP>
relative to the quasar's rest frame, is found in the HST Faint Object
Spectrograph spectrum. A similar C IV broad absorption line may also
be present in the low-resolution IUE spectrum. Historic light curves
in the X-ray, UV, and optical bands indicate that the variability
amplitude in the UV and optical bands is much smaller than in the X-ray
band. The QSO can be classified as X-ray weak only on one occasion
out of five X-ray observations. An analysis of the long-term behavior
of several other X-ray-weak objects shows no indications of a similar
large X-ray variability.
---------------------------------------------------------
Title: Ionized ultraviolet and soft X-ray absorption in the
low-redshift active galactic nucleus PG 1126-041
Authors: Wang, T. G.; Brinkmann, W.; Wamsteker, W.; Yuan, W.; Wang,
J. X.
1999MNRAS.307..821W Altcode: 1999astro.ph..3428W
We present here the analysis of ultraviolet spectra from IUE and
an X-ray spectrum from ROSAT PSPC observations of the X-ray-weak,
far-infrared-loud AGN, PG 1126-041 (Mrk 1298). The first UV spectra
taken in 1992 June, simultaneously with ROSAT, show strong absorption
lines of Nv, Civ and Siiv, extending over a velocity range from -1000
to -5000kms^-1 with respect to the corresponding line centre. Our
analysis shows that the broad emission-line region (BELR) is, at least
partially, covered by the material causing these absorption lines. In
the IUE spectrum taken in 1995 January, the continuum was a factor of
2 brighter and the UV absorption lines are found to be considerably
weaker than in 1992, but little variation in the emission-line fluxes
is found. With UV spectral indices of alpha_UV~=1.82 and 1.46 for
the 1992 and 1995 data, the far-UV spectrum is steep. Based on the
emission-line ratios and the broad-band spectral energy distribution, we
argue that the steepness of the UV spectrum is unlikely to be caused by
reddening. The soft X-ray emission in the ROSAT band is weak. A simple
power-law model yields a very poor fit with a UV-to-X-ray spectral
index alpha_UVX=2.3. Highly ionized (warm) absorption is suggested
by the ROSAT data. After correcting for a warm absorber, the optical
to X-ray spectral slope is close to the average of alpha_UVX~=1.67
for radio-quiet quasars. From photoionization calculations we find
the following results. (1) A single-zone absorption model cannot
explain simultaneously the UV absorption lines and the ionized X-ray
absorption if metal abundances are solar. Furthermore, in order to be
consistent with the equivalent width of the observed Lyalpha absorption
line, the turbulent velocity of the warm absorber must be less than
190kms^-1, which imposes serious constraints on a disc wind model. (2)
The UV absorption lines and their variability cannot be explained by
a single-zone model with solar abundances and the large variability
in the absorption lines suggests that Civ and Nv absorption lines are
not severely saturated. (3) The absorption of the ionizing continuum
by warm material strongly affects the emission-line spectrum.
---------------------------------------------------------
Title: How Saturated Are Absorption Lines in the Broad Absorption
Line Quasar PG 1411+442?
Authors: Wang, T. G.; Wang, J. X.; Brinkmann, W.; Matsuoka, M.
1999ApJ...519L..35W Altcode: 1999astro.ph..5054W
Recently, convincing evidence was found for extremely large
X-ray absorption by column densities greater than 10<SUP>23</SUP>
cm<SUP>-2</SUP> in broad absorption line quasars. One consequence of
this is that any soft X-ray emission from these QSOs would be the
scattered light or leaked light from partially covering absorbing
material. A detection of the unabsorbed soft X-ray and absorbed hard
X-ray component will allow us to determine the total column density
as well as the effective covering factor of the absorbing material,
which are difficult to obtain from the UV absorption lines. Brinkmann
et al. recently showed that both the unabsorbed and absorbed components
are detected in the nearby very bright broad absorption line quasar PG
1411+442. In this Letter, we make a further analysis of the broadband
X-ray spectrum and the UV spectrum from the Hubble Space Telescope
and demonstrate that broad absorption lines are completely saturated
at the bottom of absorption troughs.
---------------------------------------------------------
Title: Rapidly Variable Fe Kα Line in NGC 4051
Authors: Wang, J. X.; Zhou, Y. Y.; Xu, H. G.; Wang, T. G.
1999ApJ...516L..65W Altcode: 1999astro.ph..4321W
We present a detailed analysis on the variability of the Fe K
emission line in NGC 4051 using ASCA data. Through simple Gaussian
line fits, we find not only obvious Fe K line variability with
no significant difference in the X-ray continuum flux between
two ASCA observations that were separated by ~ 440 days, but also
rapid variability of the Fe K line on timescales ~10<SUP>4</SUP>
s within the second observation. During the second observation, the
line is strong (EW=733<SUP>+206</SUP><SUB>-219</SUB> eV) and broad
(σ=0.96<SUP>+0.49</SUP><SUB>-0.35</SUB> keV) when the source is
brightest and becomes weaker (EW=165<SUP>+87</SUP><SUB>-86</SUB> eV) and
narrower (σ<0.09 keV) while the source is weakest. The equivalent
width of the Fe K line correlates positively with the continuum flux,
which shows an opposite trend with another Seyfert type 1 galaxy,
MCG -6-30-15.
---------------------------------------------------------
Title: Solar sympathetic flares in two adjacent active regions
Authors: Shi, Zhong-Xian; Wang, Jing-Xiu; Luan, Di
1997AcASn..38..257S Altcode:
We describe the magnetic configurations of a group of two-ribbon flares
in NOAA 6233 and their temporally correlated one-ribbon flares in NOAA
6240, and also the topological connectivity between the two active
regions. The analyses show that the three one-ribbon flares took place
in a unipolar flux region of positive polarity, which seems to be
connected through a set of high-lying magnetic loops with the strong
delta-sunspot, where the corresponding two-ribbon flares appeared. The
interaction between the high-lying magnetic loops and the low-lying
sheared magnetic loops in the delta-sunspot appears to be the primary
cause for the two-ribbon flares. The accelerated electrons in the
primary energy release may propagate along the high-lying magnetic loops
(or the relevant separatrices), and result in the one-ribbon flares
in NOAA 6240. Therefore, we suggest that these one-ribbon flares are
the sympathetic flares of the correlated two-ribbon flares in NOAA 6233.
---------------------------------------------------------
Title: Evolution of Magnetic Helicity in Magnetic Reconnection
Authors: Hu, Y. Q.; Xia, L. D.; Li, X.; Wang, J. X.; Ai, G. X.
1997SoPh..170..283H Altcode:
This paper presents a definition of magnetic helicity specifically
for two-dimensional magnetic fields and derives the associated
helicity equation. The newly defined helicity is closely related to
its three-dimensional counterpart and serves as a measure of the
shear of magnetic field. Based on this, a numerical simulation is
carried out on magnetic reconnection occurring in the lower solar
atmosphere. It is found that the helicity dissipation due to magnetic
reconnection is very small. A large amount of helicity is transferred
upward and escapes from the domain of the solution, and the total
helicity is approximately conserved during the magnetic reconnection
and helicity transfer. This is in support of the applicability of
a postulate, which was proposed by Taylor (1974, 1986) concerning
the approximate conservation of magnetic helicity in the presence of
resistive dissipation and magnetic reconnection in a highly conductive
laboratory plasma, to the solar atmosphere.
---------------------------------------------------------
Title: Book Review: Proceedings of the third China-Japan seminar on
solar physics / International Academic Publishers, Beijing, 1995
Authors: Wang, J. X.; Ai, G. X.; Sakurai, T.; Hirayama, T.
1996SoPh..169..225W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Flares and velocity pattern around separatrix.
Authors: Shi, Zhong-xian; Wang, Jing-xiu
1996ChA&A..20..305S Altcode:
A close relationship between flares and magnetic flux cancellation
at the photospheric layer has been observationally established in a
number of active regions. The flux cancellation precedes the flares
by a few hours up to a day. During this time a specific pattern
appears in the radial velocity field in the chromosphere, namely,
the magnetic separatrix appears as a narrow blue-shifted band while
the flares all occur in the red-shifted regions on either side. This
observation supports the identification of flux cancellation with
magnetic reconnection in the lower atmosphere and confirms that the
reconnection is closely related to fast energy release in the corona.
---------------------------------------------------------
Title: Magnetic Energy Buildup in a Quadrupole Field by Photospheric
Shear Motion
Authors: Hu, Y. Q.; Wang, J. X.; Ai, G. X.; Nie, Y. P.
1995SoPh..159..251H Altcode:
Using a two-dimensional, dissipative magnetohydrodynamic model,
this paper presents a numerical simulation of the magnetic energy
buildup in a quadrupolar field by photospheric shear motion. When
electric current density is larger than a certain critical value,
an anomalous resistivity is introduced in order to account for the
dissipation caused by instabilities in high current regions. It is
shown that like a bipolar field, a quadrupolar field can efficiently
store magnetic free energy through photospheric shear motion. Electric
current formed by shear concentrates on the separatrix and magnetic
loops rooted in areas where the shear velocity gradient is large. The
atmosphere is heated by anomalous resistive dissipation during the
shear. Both magnetic and thermal energy increases nonlinearly with
shearing displacement. When the anomalous resistivity increases or
the critical current density decreases, the growth rate reduces for
magnetic energy but goes up for thermal energy.
---------------------------------------------------------
Title: On the transport of magnetic energy and complexity to the
solar corona
Authors: Wang, Jing-xiu
1995ChA&A..19..480W Altcode:
For the active corona—a system consisting of electromagnetic
fields and particles, the only open field surface is the solar
photosphere. Interaction between the velocity and magnetic fields on the
photosphere is the primary cause of the upward transport of magnetic
energy and complexity to the corona, with the diffusion process there
also playing a role.
---------------------------------------------------------
Title: Flares and separatrices between magnetic loops
Authors: Shi, Zhong-xian; Wang, Jing-xiu; Wang, Hai-min
1995ChA&A..19..469S Altcode:
Time sequences of vector magnetograms of Hauirou and Big Bear
Solar Observatories have provided us the opportunity to identify the
individual magnetic loops and athe separatrices between them. Based on
the continuous observatin of vector magnetic field of NOAA 7469 from
4 to 12 April 1993, for the first time, the authors have identified
the magnetic loop systems and relevant separatrices for such an active
region. The observational signature ofthe cross-section of separatrices
on the photosphere is as follows: (1) High degree of magnetic shear at
or close to the separatrices; <P />(2) Steep gradient of line-of-sight
magnetic field (∼ 0.1 G/km) crossing the neutral line. <P />(3)
Flux cancellation from both sides of the separatrices. At this point
the transverse field partly changes its alignment. <P />During the
observed period, flare activity took place repeatedly in the vicinity
of the separatrices.
---------------------------------------------------------
Title: Preflare State
Authors: Rust, David M.; Sakurai, Takashi; Gaizauskas, Victor; Hofmann,
Axel; Martin, Sara F.; Priest, Eric R.; Wang, Jing-Xiu
1994SoPh..153....1R Altcode:
Discussion on the preflare state held at the Ottawa Flares 22
Workshop focused on the interpretation of solar magnetograms and
of Hα filament activity. Magnetograms from several observatories
provided evidence of significant build up of electric currents in
flaring regions. Images of X-ray emitting structures provided a clear
example of magnetic relaxation in the course of a flare. Emerging
and cancelling magnetic fields appear to be important for triggering
flares and for the formation of filaments, which are associated with
eruptive flares. Filaments may become unstable by the build up of
electric current helicity. Examples of heliform eruptive filaments
were presented at the Workshop. Theoretical models linking filaments
and flares are briefly reviewed.
---------------------------------------------------------
Title: A method for resolving the 180-degree ambiguity in the observed
transverse field direction
Authors: Wang, Jing-Xiu
1994ChA&A..18Q.355W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A preliminary treatment of data from the full-disk magnetograph
Authors: Liu, Yang; Song, Guo-feng; Wang, Jing-shan; Wang, Jing-xiu
1994ChA&A..18..319L Altcode:
A full-disk magnetogram obtained with the full-disk magnetograph of
Huairou Solar Observing Station shows similar morphological features and
magnetic field intensities as in traditional small scale magnetograms
obtained by the solar magnetic field telescope at the same site.
---------------------------------------------------------
Title: An Alternative Method for Removing the 180DEG Ambiguity of
the Observed Transverse Field Direction
Authors: Wang, J. X.
1994AcApS..14..166W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Study of Data Obtained by Full Disk Magnetograph
Authors: Liu, Y.; Song, G. F.; Wang, J. S.; Wang, J. X.
1994AcApS..14..191L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Shear Angle of Vector Magnetic Field
Authors: Lu, Y. P.; Wang, J. X.; Wang, H. N.
1993AcApS..13..291L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A New Method of Calculating the Vertical Current in Solar
Active Regions
Authors: Wang, J. X.
1993AcASn..34..436W Altcode: 1993AcASn..34..438W
No abstract at ADS
---------------------------------------------------------
Title: An instance of the localized chromospheric polarity reversal
Authors: Wang, Jing-Xiu; Shi, Zhong-Xian
1992ChA&A..16..325W Altcode:
At the chromospheric level, a localized magnetic feature with polarity
opposite to the underlying photospheric magnetic field has been
observed in a rapidly formed sunspot. The strength of this reversed
polarity is several hundred gauss. Seven subflares, centering around
the reversed polarity, have been identified in observation of nine
hours. The flares showed progressive increase in size and extent with
the develop- ment of the reversed polarity. The bipolar feature above
the unipolar magnetic flux can only mean that a bundle of magnetic lines
of force has been kinked or knotted, or a self-closed flux system has
been developed above the photosphere.
---------------------------------------------------------
Title: Lorentzian contributions to x-ray lineshapes in Si(Li)
spectroscopy
Authors: Campbell, J. L.; Wang, J. -X.
1992XRS....21..223C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The relation between the twisting motion of a quiescent
filament and the magnetic field
Authors: Shi, Zhong-Xian; Wang, Jing-Xiu
1992ChA&A..16..350S Altcode:
The twisting motion of a quiescent filament in AR5572 was observed on 8
July 1989. Based on the time sequence of magnetograms, Hβ fitergrams
and Hβ Dopplergrams obtained at Huairou Solar Observing Station of
Beijing Astronomical Observatory, the twisting motion of the filament
is identified to be related to three cancelling magnetic features in
the filament channel.
---------------------------------------------------------
Title: Osmium-Iridium Correlation and Osmium Isotopic Composition
in Some Geological Boundaries and Meteorites
Authors: Liu, Y. Z.; Wang, J. X.; Mao, X. Y.; Chai, C. F.
1992Metic..27Q.251L Altcode:
Since the pioneering study of Alvarez et al. on K/T boundary event, Ir
has long been considered to be the main indicator of extraterrestrial
materials in boundaries, while little work about Os and its isotopic
composition have been done. In this work a sophisticated radiochemical
separation procedure together with neutron activation analsis (NAA)
method was established for the determination of Os in some geological
boundaries (P epsilon/epsilon, K/T, D/C, O/S, P/T). Combined with our
early work--determination of Ir abundances [1], the sources of boundary
events were deciphered by using the Os/Ir ratios. Simultaneously
^184Os/^190Os ratios in K/T boundaries, as well as inclusions of
Allende chondrite and acid-insoluble residues of iron meteorites
(Nandan, Jianshi, Longchang) were determined to search for the Os
isotopic composition anomalies resulted from the extrasolar components
by RNAA. The results show that the Os abundances exhibit a positive
correlation with the Ir abundances for overall K/T boundary samples,
but only the Os/Ir ratios of K/T boundaries, with the average of 0.98
+- 0.55, are in excellent agreement with 1.01 of the solar system
[2], Accordingly, it provides new evidence for an extraterrestrial
source of the K/T event. The results of ^184Os/^190Os ratios,
with uncertainties of less than 1%, indicate there is no remarkable
^184Os/^190Os ratio anomaly in the K/T boundary samples, which implies
the impacting matter may be from the solar system not the extrasolar,
while no anomaly exists in the inclusions of Allende chondrite and
acid-insoluble residues of iron meteorites, which disagree with the
results obtained by Goel [3]. REFERENCES [1] Chai Chifang (1988)
Isotopenpraxis 24, pp. 257-272. [2] Anders E. and Grevesse N. (l989)
Geochim. Cosmochim. Acta 53, 197-214. [3] Goel P.S.(1987) Proc. Indian
Acad. Sci. (Earth Planet. Sci), 96, pp. 81-102.
---------------------------------------------------------
Title: An approach to the development of magnetic shear
Authors: Wang, Jing-xiu
1992ChA&A..16..207W Altcode:
In view of an approximate description of magnetic shear by non-potential
character of a force-free magnetic field, the force-free factor
α would be a measure of magnetic shear, and the shear development
would be analytically described by a differential equation dα/dt=
1/β <SUP>2</SUP>∇· G+ V·∇α, where, G = ∂B/∂t × B, might
be called as the generation function of magnetic shear. It is clearly
shown by this equation that the magnetic shear is generated by local
dynamo action resulting from the interaction between magnetic field and
plasma motion. It is also illustrated that the squeezing and pressing
of opposite polarity fields, the flux emergence and submergence would
be as effective as shear motion in producing magnetic shear.
---------------------------------------------------------
Title: Direct indication of magnetic reconnection in solar photosphere
Authors: Wang, Jing-Xiu; Shi, Zhong-Xian
1992AcApS..11..389W Altcode:
A direct indication of magnetic reconnection in solar photosphere
has been found for the first time with the aid of the time sequence
of vector magnetograms. The reconnection takes place in the interface
between one pole of an emerging flux region and the old flux of opposite
polarity. It occurs well after a subflare with X-ray classification
of C2.9 when flux cancellation in the interface had lasted for several
hours. It is suggested that the reconnection in the photosphere would
be a common phenomenon on the sun.
---------------------------------------------------------
Title: An example of localized chromospheric polarity reversal
Authors: Wang, Jing-Xiu; Shi, Zhong-Xian
1992AcASn..33...95W Altcode:
In the chromosphere, a localized magnetic feature with polarity opposite
to the underlying photospheric magnetic field is observed above a fast
formed sunspot. The strength of this reversal polarity is as strong
as several hundred gauss. Centering around the reversal polarity,
seven subflares are observed during nine hours before and after the
reversal. Each flare shows progressively increasing size and spatial
extent with the development of the reversal polarity. The reversal
polarity above the photosphere can only mean that the magnetic lines
of force have been kinked, twisted or knotted, or a close flux system
has been formed above the photosphere. This newly observed phenomenon
has not yet been possible to predict by either the current sunspot
models or flare models.
---------------------------------------------------------
Title: Direct indication of magnetic reconnection in solar photosphere
Authors: Wang, Jing-xiu; Shi, Zhong-xian
1992ChA&A..16...71W Altcode:
A direct indication of magnetic reconnection in solar photosphere
has been found for the first time with the aid of the time sequence
of vector magnetograms. The reconnection takes place in the interface
between one pole of an emerging flux region and the old flux of opposite
polarity. It occurs well after a subflare with X-ray classification
of C2.9 when flux cancellation in the interface had lasted for several
hours. It is suggested that the reconnection in the photosphere would
be a common phenomenon on the sun.
---------------------------------------------------------
Title: The Relation Between the Twisting Motion of a Quiescent
Filament and the Magnetic Field
Authors: Shi, Z. X.; Wang, J. X.
1992AcApS..12..196S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Search for Celestial Gamma-Ray Point Sources with the Tibet
Air Shower Array
Authors: Amenomori, M.; Bai, Z. W.; Cao, Z.; Ding, L. K.; Hibino, K.;
Hotta, N.; Huang, Q.; Huo, A. X.; Jia, H. G.; Jiang, G. Z.; Jiao,
S. Q.; Kajino, F.; Kasahara, K.; Labaciren; Mei, D. M.; Meng, L.;
Mimaciren; Mizutani, K.; Mu, J.; Nanjo, H.; Nishizawa, M.; Nusang;
Ohnishi, M.; Ohta, I.; Ren, J. R.; Saito, T.; Sakata, M.; Shi, Z. Z.;
Shibata, M.; Shirai, T.; Sun, X. X.; Sugimoto, H.; Tai, A.; Taira,
K.; Tan, Y. H.; Tateyama, N.; Torii, S.; Wang, H.; Wang, J. X.; Wen,
C. Z.; Yamamoto, Y.; Yang, H. M.; Yu, G. C.; Yuan, P.; Yuda, T.; Zeng,
J. G.; Zhao, C. H.; Zhang, C. S.; Zhang, H. M.; Zhang, L.; Zhasang;
Zhou, W. D.
1991ICRC....1..444A Altcode: 1991ICRC...22a.444A
No abstract at ADS
---------------------------------------------------------
Title: Improved model for the intensity of low-energy tailing in
Si(Li) x-ray spectra
Authors: Campbell, J. L.; Wang, J. -X.
1991XRS....20..191C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Two-dimensional power spectrum of small-scale magnetic fields
on the quiet Sun
Authors: Wang, Jing-xiu; Shi, Zhong-xian; Liu, Jian-qiang
1991ChA&A..15..239W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Status and performance of the AS array of the Tibet
AS<SUB>γ</SUB> experiment.
Authors: Tibet As Gamma Collaboration; Amenomori, M.; Bai, Z. W.; Cao,
Z.; Ding, L. K.; Feng, Z. Y.; Hibino, K.; Hotta, N.; Huang, Q.; Huo,
A. X.; Jia, H. Y.; Jiang, G. Z.; Jiao, S. Q.; Kajino, F.; Kasahara,
K.; Labaciren; Mei, D. M.; Meng, L.; Mimaciren; Mizutani, K.; Mu, J.;
Nanjo, H.; Nishizawa, M.; Nusang; Ohnishi, M.; Ohta, I.; Ren, J. R.;
Saito, T.; Sakata, M.; Shi, Z. Z.; Shibata, M.; Shirai, T.; Sun, X. X.;
Sugimoto, H.; Tai, A.; Taira, K.; Tan, Y. H.; Tateyama, N.; Torii,
S.; Wang, H.; Wang, J. X.; Wen, C. Z.; Yamamoto, Y.; Yang, H. M.; Yu,
G. C.; Yuan, P.; Yuda, T.; Zeng, J. G.; Zhao, C. H.; Zhang, C. S.;
Zhang, H. M.; Zhang, L.; Zhang, M.; Zhasang; Zhaxiciren; Zhou, W. D.
1991AIPC..220..257T Altcode:
The Tibet ASγ experiment, which has started since January, 1990, is
located at an altitude of 4300 m at Yangbaging in Tibet, China (90.5°E,
30.1°N). The air-shower array is composed of 49 scintillation counters
for fast timing, each counter having an area of 0.5 m<SUP>2</SUP>, in
a grid pattern with a spacing of 15 m and 16 density detectors. The
analysis of experimental data shows that the performance of array
is realized as expected by the Monte Carlo simulation. The detection
threshold energy for γ-rays is ≡40 TeV; the peak energy 20 TeV. The
angular resolution around 100 TeV is ≡0.5°. The systematic error of
arrival direction is considerably smaller than the angular resolution
in the concerned energy region.
---------------------------------------------------------
Title: Performance of the AS array in Tibet for search for gamma-ray
point sources.
Authors: Amenomori, M.; Bai, Z. W.; Cao, Z.; Ding, L. K.; Feng, Z. Y.;
Hibino, K.; Hotta, N.; Huang, Q.; Huo, A. X.; Jia, H. Y.; Jiang,
G. Z.; Jiao, S. Q.; Kajino, F.; Kasahara, K.; Labaciren; Mei, D. M.;
Meng, L.; Mimaciren; Mizutani, K.; Mu, J.; Nanjo, H.; Nishizawa,
M.; Nusang; Ohnishi, M.; Ohta, I.; Ren, J. R.; Saito, T.; Sakata,
M.; Shi, Z. Z.; Shibata, M.; Shirai, T.; Sun, X. X.; Sugimoto, H.;
Tai, A.; Taira, K.; Tan, Y. H.; Tateyama, N.; Torii, S.; Wang, H.;
Wang, J. X.; Wen, C. Z.; Yamamoto, Y.; Yang, H. M.; Yu, G. C.; Yuan,
P.; Yuda, T.; Zeng, J. G.; Zhao, C. H.; Zhang, C. S.; Zhang, H. M.;
Zhang, L.; Zhang, M.; Zhasang; Zhaxiciren; Zhou, W. D.
1991aame.confQ.449A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Direct Evidence of Magnetic Reconnection in Photospheric
Layer on the Sun
Authors: Wang, J. X.; Shi, Z. X.
1991AcApS..11..389W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Search for gamma-ray point sources by the fast-timing detector
array in Tibet.
Authors: Amenomori, M.; Bai, Z. W.; Cao, Z.; Ding, L. K.; Feng, Z. Y.;
Hibino, K.; Hotta, N.; Huang, Q.; Huo, A. X.; Jia, H. Y.; Jiang,
G. Z.; Jiao, S. Q.; Kajino, F.; Kasahara, K.; Labaciren; Mei, D. M.;
Meng, L.; Mimaciren; Mizutani, K.; Mu, J.; Nanjo, H.; Nishizawa,
M.; Nusang; Ohnishi, M.; Ohta, I.; Ren, J. R.; Saito, T.; Sakata,
M.; Shi, Z. Z.; Shibata, M.; Shirai, T.; Sun, X. X.; Sugimoto, H.;
Tai, A.; Taira, K.; Tan, Y. H.; Tateyama, N.; Torii, S.; Wang, H.;
Wang, J. X.; Wen, C. Z.; Yamamoto, Y.; Yang, H. M.; Yu, G. C.; Yuan,
P.; Yuda, T.; Zeng, J. G.; Zhao, C. H.; Zhang, C. S.; Zhang, H. M.;
Zhang, L.; Zhang, M.; Zhasang; Zhaxiciren; Zhou, W. D.
1991aame.confR.449A Altcode:
As the first result of the Tibet experiment the data obtained during
the week centered at the radio-burst from Cygnus X-3 on 15th of August,
1990, were analysed. But the preliminary results do not give any excess
from Cygnus X-3 in this period at the median energy 30 TeV.
---------------------------------------------------------
Title: Fast appearances and disappearances of weak intranetwork
magnetic fields
Authors: Shi, Zhong-xian; Wang, Jing-xiu; Liu, Jian-qiang; Han, Feng;
Liu, Gui-lin
1990ChA&A..14..325S Altcode:
Under good seeing conditions (<2'), the high resolution magnetic
field observation at Huairou Solar Observing Station'is capable of
detecting the intranetwork field. An analysis of some magnetograms
of 1988 September 5 shows: 1. That the observed weak intranetwork
magnetic fields (WINF) with maximum flux B between 5 and 10 G are real
structures. 2. That About 70% of the WINF became undetectable at ±
5 G level after 3.4 min and about 30% can be seen again. 3. That the
number of WINF seen decreased exponentially with time, from which
we estimated an upper limit of about 3 min for the mean life of a
WINF. 4. That a WINF is a collection of unresolved flux elements,
with a flux between 2.0(+16) and 1.0(+18) mx. Our results are similar
to those in the magnetograms of 1984 September 9 obtained by the Big
Bear Solar Observatory.
---------------------------------------------------------
Title: Two-dimensional power spectrum of small-scale magnetic fields
on the quiet sun.
Authors: Wang, Jing-Xiu; Shi, Zhong-Xian; Liu, Jian-Qiang
1990ChA&A..14..240W Altcode: 1990ChA&A..14..240.
No abstract at ADS
---------------------------------------------------------
Title: Fast appearances and disappearances of weak intranetwork
magnetic fields
Authors: Shi, Zhong-Xian; Wang, Jing-Xiu; Liu, Jian-Qiang; Han, Feng;
Liu, Gui-Lin
1990AcASn..31...63S Altcode:
Results are presented of the analysis of magnetograms obtained, under
conditions of best visibility, at the Huairou Station of the Beijing
Observatory on September 5, 1988. The magnetograms showed the existence
of weak intranetwork magnetic fields (INFs) which were appearing
and disappearing, with a maximum flux B between 5 and 10 G. Evidence
is presented that the weak appearing and disappearing INFs are real
structures; about 70 percent of INFs become undetectable at the level of
about 5 G after 3.4 min of observation; about 30 percent of INFs can be
seen again. The number of weak INFs decreases exponentially with time,
leading to an upper limit of about 3 min for the mean life of a weak
INF. It is suggested that a weak INF is a collection of unresolved
flux elements, with a flux between 2.0(+16) and 1.0(+18) Mx.
---------------------------------------------------------
Title: Two-dimensional power spectrum of small-scale magnetic fields
on the quiet sun.
Authors: Wang, Jing-Xiu; Shi, Zhong-Xian; Liu, Jian-Qiang
1990AcApS..10...96W Altcode:
Based on magnetograms of September 5, 1988, the authors constructed
a 2-D power spectrum for small-scale magnetic fields in a solar quiet
region. The preliminary results are summarized as follows. (1) The solar
magnetic fields in quiet regions are not only concentrated in discrete
flux patches, but also distributed over discrete spatial periods. (2)
The most obvious periods of small-scale fields are of supergranule
scales. There are some peaks in the power spectrum corresponding to
the spatial periods in mesogranule scales, and to the scales in between
meso- and supergranules.
---------------------------------------------------------
Title: The observed size, flux spectrum of small-scale magnetic
features.
Authors: Wang, Jing-Xiu; Shi, Zhong-Xian; Liu, Jian-Qiang; Feng, Han;
Liu, Gui-Lin
1989PBeiO..14...44W Altcode:
The observed size, flux spectrum, and spatial distribution of
small-scale magnetic features on the quiet photosphere are obtained
statistically based on the high sensitivity magnetograms acquired at
Huairou Solar Observing Station of Beijing Astronomical Observatory. The
implications of these observational results are briefly discussed.
---------------------------------------------------------
Title: The relationship between solar flare and magnetic field in
AR 5229.
Authors: Shi, Zhong-Xian; Wang, Jing-Xiu; Liu, Gui-Lin; Hang, Feng
1989PYunO...1S..87S Altcode:
Active region 5229 was studied during 13 - 18 November 1988 using
Hβ filtergrams and Fe I 5324 videomagnetograms acquired at Huairou
Solar Observing Station of Beijing Astronomical Observatory. Newly
emerging flux, magnetic shear and magnetic flux cancellation were
examined according to the evolution of magnetic fields. Preliminary
results of the analysis were summarized.
---------------------------------------------------------
Title: An example of general solar-terrestrial effects of major
solar events.
Authors: Gao, Mei-Qing; Liu, Chun-Jie; Wang, Jing-Xiu
1989PYunO...1S.180G Altcode:
The general solar-terrestrial effects including 20 parameters of major
solar events in February, 1986 are analyzed and illustrated in terms
of time sequence of various disturbances in interplanetary space,
ionosphere and geomagnetic field. The characteristics of geomagnetic
storm recorded at 6 stations are compared. The satellite anomaly and
communication disturbance are also shown.
---------------------------------------------------------
Title: The Relationship Between Solar Flare and Magnetic Field
in AR5229
Authors: Shi, Z. X.; Wang, J. X.; Liu, G. L.; Hang, F.
1989PYunO..87....1S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Interpolated Dirac-Fock Values of L-Subshell X-Ray Emission
Rates Including Overlap and Exchange Effects
Authors: Campbell, J. L.; Wang, J. -X.
1989ADNDT..43..281C Altcode:
Published theoretical L x-ray emission rates based upon a fixed atomic
potential cover the atomic number range Z = 4 to 94. However, the
presumably more accurate calculations employing different initial- and
final-state potentials have been done for only 21 values of Z. The ratio
of these two rates for each electric dipole transition as a function of
Z is fitted using polynomials in piece-wise fashion. The fixed-potential
emission rates are then renormalized by these interpolated ratios
to provide equivalent two-potential rates. The errors incurred are
generally under 0.2%.
---------------------------------------------------------
Title: A Example of General Solar-Terrestrial Effects of Major
Solar Events
Authors: Gao, M. Q.; Liu, C. J.; Wang, J. X.
1989PYunO.180....1G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The fine structure and evolution of a subflare.
Authors: Shi, Z. -X.; Chen, J.; Wang, J. -X.
1988ChJSS...8....1S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Samples from Martian Craters: Origin of the Martian Soil
by Hydrothermal Alteration of Impact Melt Deposits and Atmospheric
Interactions with Ejecta During Crater Formation
Authors: Wang, Jing-Xiu; Shi, Zhong-Xian
1988AcASn..29...48W Altcode:
On July 9, 1984, continuous magnetograms with 1-2 arcsec spatial
resolution, 2.5 min time resolution, and noise level below 5 Gauss
were obtained. Analysis of these magnetograms after calibration and
empirical corrections shows that, in addition to the transient,
mixed polarity field described by Livingston and Harvey (1975),
there is a stable type of unipolar flux form. These features have a
typical size of 2-5 arcsecs in one dimension, a total flux of (+18)
Mx, a field strength of approximately 40 G and a lifetime of several
hours. The features are called intranetwork flux concentrations (INFC).
---------------------------------------------------------
Title: Intra-network flux concentrations
Authors: Wang, Jing-xiu; Shi, Zhong-xian
1988ChA&A..12..241W Altcode:
On 1984 July 9, we obtained continuous magnetograms with 1"-2" spatial
resolution, 2.5min time resolution and noise level below 5 Gauss at
Big Bear Solar Observatory. Analysis of' these magnetograms after
calibration and empirical corrections shows that, in addition to the
transient, mixed polarity field described by Livingston and Harvey
(1975), there is a stable type of uni-polar flux forms. These features
have a typical size of 2"-5" in one dimension, a total flux of (+18)
Mx, a field strength of approximately 40G and a lifetime of several
hours. We call these Intra-Network Flux Concentrations (INFC).
---------------------------------------------------------
Title: The Structure and Evolution of Smallscale Magnetic Fields on
the Solar Surface
Authors: Wang, J. X.; Shi, Z. X.
1988PrA.....6..105W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The structure and evolution of small-scale magnetic fields
on the solar surface.
Authors: Wang, J. -X.; Shi, Z. -X.
1988PABei...6...94W Altcode:
Small-scale magnetic fields on the solar surface, a term applied to all
magnetic features and structures outside active regions, are usually
much smaller in area than a supergranule. Currently they are divided
into three categories: network magnetic fields, intranetwork magnetic
fields and ephemeral active regions (or ephemeral regions). They are
the majority of solar magnetic flux at any phase of solar cycle. Their
appearance, disappearance and evolution may play an important role
in heating the upper atmosphere. The observations of flux emergence,
cancellation, coalescence and fragmentation cause us to view the
network magnetic fields in a new way that the network fields are not
only the products of the remnant fields of decaying active regions,
but also the products of the remnant flux of ephemeral regions and
intranetwork fields.
---------------------------------------------------------
Title: Evolution of network magnetic fields of solar quiet regions
Authors: Shi, Zhong-xian; Wang, Jing-xiu
1987ChA&A..11..221S Altcode:
There are 4 types of evolution patterns of network magnetic fields:
(1) flux cancellation, the mutual disappearance of encountering fluxes
of opposite polarity, (2) flux increase by emergence of ephemeral
regions, (3) flux decrease of one polarity and (4) flux increase of one
polarity, without emergence of ephemeral regions. From a time sequence
of magnetograms of a quiet region of 1983 October 14, the evolution
of 300 network features was measured. The magnetograms have a spatial
resolution of 2 to 3 arcsec and a time resolution of about 2 hr. The
statistics show that the contribution to flux decrease by Type 3 is
1.28 times that by Type 1, and the contribution to flux increase by
Type 4 is 7 times that by Type 2.
---------------------------------------------------------
Title: Evolution of network magnetic fields of solar quiet regions
Authors: Shi, Zhong-Xian; Wang, Jing-Xiu
1987AcASn..28..111S Altcode:
The evolution of 300 quiet-region network features is followed in
a time series of longitudinal magnetograms obtained (with spatial
resolution 2-3 arcsec and time resolution about 2 h) using the VMG at
Big Bear Solar Observatory on October 10-14, 1983. The results are
presented in sample magnetograms and tables of numerical data. Four
general evolution patterns are identified: (1) flux cancellation,
(2) flux increase associated with the emergence of ephemeral regions,
(3) one-polarity flux decrease, and (4) flux increase in one polarity
without emergence of ephemeral regions. Patterns (3) and (4) are shown
to be the dominant forms of decrease and increase, respectively.
---------------------------------------------------------
Title: A comparison between hard X-ray, soft X-ray, and microwave
images and H-alpha isophote map of the 1980 november 5 flare
Authors: Shi, Zhong-xian; Wang, Jing-xiu
1987ChA&A..11..162S Altcode:
Filtergrams of the 1B/M1-M4 Hα flare of 1980 November 5 were digitized
and the resulting isophote map compared with the hard X-, soft X,
and microwave images. It was found: 1) During the first maximum. the
high energy electrons did not penetrate the chromosphere. The Hα flare
was probably caused by heat conduction from the (+7)-(+8) K hot plasma
which generated the hard and soft X emissions. 2) The second maximum
can be inferred to have been caused by bremsstrahlung of high energy
electrons. The Hα maximum lagged behind the X-ray burst by not more
than 5 seconds. 3) During the flash phase the area and the intensity
of Hα emission increased in step with each other. 4) From the changes
in the transverse magnetic field as outlined by Hα fibrils, (+31) ergs
of magnetic energy is estimated to have been released in this flare.
---------------------------------------------------------
Title: Fine structure and evolution of a subflare.
Authors: Shi, Z. -X.; Chen, J.; Wang, J. -X.
1987PBeiO..10...69S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Evolution of Network Magnetic Fields of the Solar Quiet
Regions
Authors: Shi, Z. X.; Wang, J. X.
1987AcApS..28..119S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The meteorites of Boxian and its minerals.
Authors: Wang, K. -R.; Wang, J. -X.; Li, X. -M.
1987KexT...32..545W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Do moving magnetic features represent sunspot decay?
Authors: Wang, J. -X.; Martin, S. F.; Livi, S. H. B.
1987PBeiO..10...58W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A comparison between hard X-ray, soft X-ray, microwave burst
images and Hα isophote map of the flare on November 5, 1980.
Authors: Shi, Z. -X.; Wang, J. -X.
1987ChJSS...7...18S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the propagation of magneto-acoustic-gravity waves
Authors: Wang, Jing-xiu
1986ChA&A..10..291W Altcode:
An analysis of magneto-acoustic-gravity waves in the case of an
isothermal atmosphere permeated by a uniform magnetic field is
presented. The general solution is expressed in terms of generalized
hypergeometric functions. It can be used in numerical simulation of
oscillations in a magnetic atmosphere. It is shown that the elliptically
polarized magneto-acoustic-gravity waves consist of a pair of surface
waves and a pair of body waves above the cut-off frequency. The body
waves along the magnetic field are similar to acoustic waves in an
atmosphere and their cut-off frequency is unaffected by magnetic
field. The transverse oscillation decreases with height. For the
usual boundary condition, the longitudinal oscillation decreases with
height; however, in some cases, it may contain terms that increase
with height. The solution is singular on a family of ellipses in
the frequency - horizontal wave number plane. Near these ellipses,
the wave components grow indefinitely.
---------------------------------------------------------
Title: On the propagation of magneto-acoustic-gravity waves
Authors: Wang, Jing-Xiu
1986AcApS...6..231W Altcode:
An analysis of magnetoacoustic-gravity waves in the case of an
isothermal atmosphere permeated by a uniform magnetic field is
presented. The general solution is expressed in terms of generalized
hypergeometric functions. It can be used in numerical simulation of
oscillations in a magnetic atmosphere. It is shown that the elliptically
polarized magnetoacoustic-gravity wave consist of a pair of surface
waves and a pair of body waves above the cut-off frequency. The body
waves along the magnetic field are similar to acoustic waves in an
atmosphere, and their cut-off frequency is unaffected by magnetic
field. The transverse oscillation decreases with height. For the
usual boundary condition, the longitudinal oscillation decreases with
height; however, in some cases, it may contain terms that increase
with height. The solution is singular on a family of ellipses in
the frequency - horizontal wave number plane. Near these ellipses,
the wave components grow indefinitely.
---------------------------------------------------------
Title: The Hα characteristics of hard X-ray bursts.
Authors: Shi, Zhong-Xian; Wang, Jing-Xiu
1986ChJSS...6..243S Altcode:
The following results are obtained from the examination of 50 H-alpha
flares. All flares with HXRBS are detectable from the emission of
H-alpha + or - 2 A. They have at least two H-alpha kernels located in
the opposite polarity regions. The H-alpha brightenings start earlier
than HXRBS, while the H-alpha peaks, which correspond to the spikes of
HXRBS very well, come later than that of HXRBS by several seconds. If
the count rates of HXRBS are more than 1000, the kernels of H-alpha
+2 A cover the penumbra; if the count rates are less than 200, the
kernels do not cover the penumbra.
---------------------------------------------------------
Title: The boundary value problem of the solar force-free magnetic
field with constant α and its analytical solution
Authors: Chen, Z. -C.; Wang, J. -X.
1986SoPh..103..317C Altcode:
In this paper we present a physical model which uses boundary
conditions which seem to correspond more appropriately to actual
situations. A boundary value problem of solar force-free magnetic
field with constant α has been specified to represent the discretely
concentrated characteristics of the longitudinal magnetic field on
the photosphere. A unique analytical solution for the problem is
obtained by a more strict method in mathematical physics. The most
distinctive feature of our method is to make the solution be the
superposition of the fields of single sources which are described by
the physical parameters of corresponding sunspots on the photosphere,
such as their position, strength, decay rates and the extent of the same
polarity. The solution enables us to make an analytical description of
the configuration of the magnetic field in the chromosphere and corona,
and to investigate more conveniently its development as the foot points
on the photosphere evolve.
---------------------------------------------------------
Title: A unique solution for the boundary value problem of the solar
force free magnetic field with constant α.
Authors: Chen, Z. -C.; Wang, J. -X.
1985KexT...30..768C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The oscillator strength of hydrogen lines
Authors: Shi, Zhong-xian; Wang, Jing-xiu
1984ChA&A...8...94S Altcode:
We give a formal expression for the dependence of hydrogen line
oscillator strength on departure from LTE and propose a method for
determining this departure in the various sub-levels of the hydrogen
atom in solar prominences. Results for 10 solar prominences are
given. Finally, we discuss the possible implications of a smaller
population in the 2p level than in the 2s level.
---------------------------------------------------------
Title: A method of analysing the emission lines of solar prominences
Authors: Wang, Jing-xiu; Shi, Zhong-xian
1983ChA&A...7..269W Altcode:
A new method of analysing the emission spectrum of solar prominences
is presented, in which the source function is allowed to vary with
optical depth. Least-squares fitting of the observed profile determines
simultaneously the optical depth τ <SUB>0</SUB>, the Doppler width
Δλ <SUB>D</SUB> and the factor α characterising the variation of the
source function. This method is applied to the early Balmer lines in
ten prominences of Ref. [1]. The results show that the source function
of the self-reversed H <SUB>α</SUB> line increases towards the centre
of the prominence, the value at the centre is 1.2-2.5 times the value
at the edge. Neglect of this variation will give too large values
of τ <SUB>0</SUB>. The degree of attenuation by selfabsorption also
depends on this variation. Discussion of the variation gives support
to the view that the main exciting mechanism in solar prominences is
the scattering of the incident radiation.
---------------------------------------------------------
Title: A method of analyzing the emission lines of solar prominences
Authors: Wang, J. -X.; Shi, Z. -X.
1983AcApS...3..169W Altcode:
A new method of analyzing the emission spectrum of solar prominences
is presented, in which the source function is allowed to vary with
optical depth. Least-squares fitting of the observed profile determines
simultaneously the optical depth T(0), the Doppler width, and the factor
characterizing the variation of the source function. This method is
applied to the early Balmer lines in ten prominences of Ye (1961). The
results show that as the source function of the self-reversed H-alpha
line increases towards the center of the prominence, the value at
the center is 1.2 - 2.5 times the value at the edge. Neglect of this
variation will give too large values of T(0). The degree of attenuation
by self-absorption also depends on this variation. Discussion of the
variation gives support to the view that the main exciting mechanism
in solar prominences is the scattering of the incident radiation.
---------------------------------------------------------
Title: The oscillator strength of hydrogen lines
Authors: Shi, Z. -X.; Wang, J. -X.
1983AcApS...3..327S Altcode:
A formal expression is given for the dependence of hydrogen-line
oscillator strength on departure form LTE, and a method is proposed for
determining this departure in the various sublevels of the hydrogen
atom in solar prominences. Results for 10 solar prominences are
given. Finally, the possible implications of a smaller population in
the 2p level than in the 2s level are discussed.
