Author name code: roy
ADS astronomy entries on 2022-09-14
author:"Roy, Jean-Rene"
------------------------------------------------------------------------
Title: The GMRT High Resolution Southern Sky Survey for Pulsars and
Transients. III. Searching for Long-period Pulsars
Authors: Singh, S.; Roy, J.; Panda, U.; Bhattacharyya, B.; Morello,
V.; Stappers, B. W.; Ray, P. S.; McLaughlin, M. A.
Bibcode: 2022ApJ...934..138S
Altcode: 2022arXiv220600427S
Searching for periodic non-accelerated signals in the presence of ideal
white noise using the fully phase-coherent fast-folding algorithm (FFA)
is theoretically established as a more sensitive search method than the
fast Fourier transform (FFT) search with incoherent harmonic summing. In
this paper, we present a comparison of the performance of an FFA search
implementation using RIPTIDE and an FFT search implementation using
PRESTO, over a range of signal parameters with white noise and with
real telescope noise from the Giant Meterwave Radio Telescope (GMRT)
High Resolution Southern Sky (GHRSS) survey with the upgraded GMRT
(uGMRT). We find that the FFA search with appropriate de-reddening
of the time series performs better than the FFT search with spectral
whitening for long-period pulsars under real GHRSS noise conditions. We
describe an FFA-search pipeline implemented for the GHRSS survey looking
for pulsars over a period of 0.1-100 s and up to a dispersion measure of
500 pc cm-3. We processed GHRSS survey data covering ~1500
deg2 of the sky with this pipeline. We re-detected 43 known
pulsars with a better signal-to-noise ratio in the FFA search than
in the FFT search. We also report the discovery of two new pulsars,
including a long-period pulsar with a short duty cycle, using this
FFA-search pipeline. A population of long-period pulsars with periods
of several seconds or higher could help constrain the pulsar death line.
Title: Serendipitous Discovery of Three Millisecond Pulsars with
the GMRT in Fermi-directed Survey and Follow-up Radio Timing
Authors: Bhattacharyya, B.; Roy, J.; Freire, P. C. C.; Ray, P. S.;
Johnson, T. J.; Gupta, Y.; Bhattacharya, D.; Kaninghat, A.; Ferrara,
E. C.; Michelson, P. F.
Bibcode: 2022ApJ...933..159B
Altcode:
We report the discovery of three millisecond pulsars (MSPs): PSRs
J1120-3618, J1646-2142, and J1828+0625 with the Giant Metrewave
Radio Telescope (GMRT) at a frequency of 322 MHz using a 32 MHz
observing bandwidth. These sources were discovered serendipitously
while conducting the deep observations to search for millisecond radio
pulsations in the directions of unidentified Fermi Large Area Telescope
(LAT) γ-ray sources. We also present phase coherent timing models for
these MSPs using ~5 yr of observations with the GMRT. PSR J1120-3618
has a 5.5 ms spin period and is in a binary system with an orbital
period of 5.6 days and minimum companion mass of 0.18 M ⊙,
PSR J1646-2142 is an isolated object with a spin period of 5.8 ms, and
PSR J1828+0625 has a spin period of 3.6 ms and is in a binary system
with an orbital period of 77.9 days and minimum companion mass of 0.27
M ⊙. The two binaries have very low orbital eccentricities,
in agreement with expectations for MSP-helium white dwarf systems. Using
the GMRT 607 MHz receivers having a 32 MHz bandwidth, we have also
detected PSR J1646-2142 and PSR J1828+0625, but not PSR J1120-3618. PSR
J1646-2142 has a wide profile, with significant evolution between 322
and 607 MHz, whereas PSR J1120-3618 exhibits a single peaked profile
at 322 MHz and PSR J1828+0625 exhibits a single peaked profile at both
the observing frequencies. These MSPs do not have γ-ray counterparts,
indicating that these are not associated with the target Fermi LAT
pointing emphasizing the significance of deep blind searches for MSPs.
Title: A novel greedy approach to harmonic summing using GPUs
Authors: Adámek, K.; Roy, J.; Armour, W.
Bibcode: 2022A&C....4000621A
Altcode: 2022arXiv220212817A
One-dimensional incoherent harmonic summing is a technique used to
improve the sensitivity of Fourier domain search methods. In time-domain
radio astronomy, the harmonic sum is a part of the Fourier domain
periodicity search, which aims to detect isolated single pulsars. We
present a new harmonic sum algorithm based on the greedy approach and
an implementation of this on NVIDIA GPUs using the CUDA programming
language. The new algorithm determines which samples to add according
to short-term gains. We present an evaluation of the sensitivity of
the new approach and its performance against the PRESTO harmonic sum
a standard used in radio astronomy. The new Greedy harmonic sum has,
on average, 20% higher sensitivity whilst it has the same performance
as the standard algorithm. This work forms part of the AstroAccelerate
project which is a GPU accelerated software package for processing
time-domain radio astronomy data.
Title: Adelaide Ames (1900–32) and the Shapley-Ames Catalog
of Galaxies
Authors: Roy, Jean-René
Bibcode: 2022AntAs..16...70R
Altcode:
The history of science is punctuated by landmark publications. One such
example was the galaxy survey that came to be known as the Shapley-Ames
Catalog (1932). Its list of 1,249 of the brightest galaxies provided
the basis for several atlases of galaxies published in the second half
of the 20th century. Its two authors were a contrasting pair: Harlow
Shapley, the director of the Harvard College Observatory, was already
renowned, while co-author Adelaide Ames was a young astronomer engaged
in the new field of galaxy studies who died tragically by drowning
at the age of 32, curtailing a promising career. By the time of her
death she had published 32 papers, almost all of them on galaxies;
several were on the Coma-Virgo extension, a relatively narrow band
of galaxies extending over 60° in declination. This paper looks at
the life and work of Adelaide Ames and examines how the Shapley-Ames
Catalog contributed to galaxy classification systems.
Title: VizieR Online Data Catalog: Gravitational-wave freq. limits
for PSRJ1653-0158 (Nieder+, 2020)
Authors: Nieder, L.; Clark, C. J.; Kandel, D.; Romani, R. W.; Bassa,
C. G.; Allen, B.; Ashok, A.; Cognard, I.; Fehrmann, H.; Freire, P.;
Karuppusamy, R.; Kramer, M.; Li, D.; Machenschalk, B.; Pan, Z.; Papa,
M. A.; Ransom, S. M.; Ray, P. S.; Roy, J.; Wang, P.; Wu, J.; Aulbert,
C.; Barr, E. D.; Beheshtipour, B.; Behnke, O.; Bhattacharyya, B.;
Breton, R. P.; Camilo, F.; Choquet, C.; Dhillon, V. S.; Ferrara,
E. C.; Guillemot, L.; Hessels, J. W. T.; Kerr, M.; Kwang, S. A.;
Marsh, T. R.; Mickaliger, M. B.; Pleunis, Z.; Pletsch, H. J.; Roberts,
M. S. E.; Sanpa-Arsa, S.; Steltner, B.
Bibcode: 2022yCat..19029046N
Altcode:
We searched for gamma-ray pulsations in the arrival times of photons
observed by the Fermi-LAT between 2008-Aug-03 and 2018-Apr-16 (MJDs
54681 and 58224). The data set used here consisted of N=354009 photons,
collected over a period of 3542 days. Following the pulsar discovery,
we extended this data set to 2020-Feb-23 (MJD58902). See Section 2. (1 data file).
Title: A gamma-ray pulsar timing array constrains the nanohertz
gravitational wave background
Authors: FERMI-LAT Collaboration; Ajello, M.; Atwood, W. B.; Baldini,
L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.;
Berretta, A.; Bhattacharyya, B.; Bissaldi, E.; Blandford, R. D.;
Bloom, E.; Bonino, R.; Bruel, P.; Buehler, R.; Burns, E.; Buson, S.;
Cameron, R. A.; Caraveo, P. A.; Cavazzuti, E.; Cibrario, N.; Ciprini,
S.; Clark, C. J.; Cognard, I.; Coronado-Blázquez, J.; Crnogorcevic,
M.; Cromartie, H.; Crowter, K.; Cutini, S.; D'Ammando, F.; De Gaetano,
S.; de Palma, F.; Digel, S. W.; Di Lalla, N.; Fana Dirirsa, F.; Di
Venere, L.; Domínguez, A.; Ferrara, E. C.; Fiori, A.; Franckowiak,
A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gammaldi, V.; Gargano, F.;
Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Green, D.;
Grenier, I. A.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Harding,
A. K.; Hays, E.; Hewitt, J. W.; Horan, D.; Hou, X.; Jóhannesson, G.;
Keith, M. J.; Kerr, M.; Kramer, M.; Kuss, M.; Larsson, S.; Latronico,
L.; Li, J.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano,
P.; Maldera, S.; Manfreda, A.; Martí-Devesa, G.; Mazziotta, M. N.;
Mereu, I.; Michelson, P. F.; Mirabal, N.; Mitthumsiri, W.; Mizuno,
T.; Monzani, M. E.; Morselli, A.; Negro, M.; Nieder, L.; Ojha, R.;
Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.;
Parthasarathy, A.; Pei, Z.; Persic, M.; Pesce-Rollins, M.; Pillera,
R.; Poon, H.; Porter, T. A.; Principe, G.; Racusin, J. L.; Rainò,
S.; Rando, R.; Rani, B.; Ransom, S. M.; Ray, P. S.; Razzano, M.;
Razzaque, S.; Reimer, A.; Reimer, O.; Roy, J.; Sánchez-Conde, M.;
Saz Parkinson, P. M.; Scargle, J.; Scotton, L.; Serini, D.; Sgrò, C.;
Siskind, E. J.; Smith, D. A.; Spandre, G.; Spiewak, R.; Spinelli, P.;
Stairs, I.; Suson, D. J.; Swihart, S. J.; Tabassum, S.; Thayer, J. B.;
Theureau, G.; Torres, D. F.; Troja, E.; Valverde, J.; Wadiasingh,
Z.; Wood, K.; Zaharijas, G.
Bibcode: 2022Sci...376..521F
Altcode: 2022arXiv220405226A
After large galaxies merge, their central supermassive black
holes are expected to form binary systems. Their orbital motion
should generate a gravitational wave background (GWB) at nanohertz
frequencies. Searches for this background use pulsar timing arrays,
which perform long-term monitoring of millisecond pulsars at radio
wavelengths. We used 12.5 years of Fermi Large Area Telescope data to
form a gamma-ray pulsar timing array. Results from 35 bright gamma-ray
pulsars place a 95% credible limit on the GWB characteristic strain of
1.0 × 10−14 at a frequency of 1 year–1. The
sensitivity is expected to scale with tobs, the observing
time span, as tobs−13/6. This direct measurement provides an
independent probe of the GWB while offering a check on radio noise
models.
Title: AstroSat science support cell
Authors: Roy, J.; Alam, Md. S.; Balamurugan, C.; Bhattacharya, D.;
Bhoye, P.; Dewangan, G. C.; Hulsurkar, M.; Mali, N.; Misra, R.;
Pore, A.
Bibcode: 2021JApA...42...28R
Altcode: 2021arXiv210401609R
AstroSat is India's first dedicated multi-wavelength space observatory
launched by the Indian Space Research Organisation (ISRO) on 28
September 2015. After launch, the AstroSat Science Support Cell (ASSC)
was set up as a joint venture of ISRO and the Inter-University Centre
for Astronomy and Astrophysics (IUCAA) with the primary purpose of
facilitating the use of AstroSat, both for making observing proposals
and for utilising archival data. The ASSC organises meetings, workshops
and webinars to train users in these activities, runs a help desk to
address user queries, provides utility tools and disseminates analysis
software through a consolidated web portal. It also maintains the
AstroSat Proposal Processing System (APPS) which is deployed at
ISSDC, a software platform central to the workflow management of
AstroSat operations. This paper illustrates the various aspects of
ASSC functionality.
Title: Multifrequency study of the peculiar pulsars PSR B0919+06
and PSR B1859+07
Authors: Rajwade, K. M.; Perera, B. B. P.; Stappers, B. W.; Roy, J.;
Karastergiou, A.; Rankin, J. M.
Bibcode: 2021MNRAS.506.5836R
Altcode: 2021MNRAS.tmp.1749R; 2021arXiv210702059R
Since their discovery more than 50 years ago, broad-band radio studies
of pulsars have generated a wealth of information about the underlying
physics of radio emission. In order to gain some further insights into
this elusive emission mechanism, we performed a multifrequency study
of two very well-known pulsars, PSR B0919+06 and PSR B1859+07. These
pulsars show peculiar radio emission properties whereby the emission
shifts to an earlier rotation phase before returning to the nominal
emission phase in a few tens of pulsar rotations (also known as
'swooshes'). We confirm the previous claim that the emission during
the swoosh is not necessarily absent at low frequencies and the single
pulses during a swoosh show varied behaviour at 220 MHz. We also confirm
that in PSR B0919+06, the pulses during the swoosh show a chromatic
dependence of the maximum offset from the normal emission phase with the
offset following a consistent relationship with observing frequency. We
also observe that the flux density spectrum of the radio profile
during the swoosh is inverted compared to the normal emission. For PSR
B1859+07, we have discovered a new mode of emission in the pulsar that
is potentially quasi-periodic with a different periodicity than is seen
in its swooshes. We invoke an emission model previously proposed in the
literature and show that this simple model can explain the macroscopic
observed characteristics in both pulsars. We also argue that pulsars
that exhibit similar variability on short time-scales may have the
same underlying emission mechanism.
Title: Evaluating Low-frequency Pulsar Observations to Monitor
Dispersion with the Giant Metrewave Radio Telescope
Authors: Jones, M. L.; McLaughlin, M. A.; Roy, J.; Lam, M. T.; Cordes,
J. M.; Kaplan, D. L.; Bhattacharyya, B.; Levin, L.
Bibcode: 2021ApJ...915...15J
Altcode: 2020arXiv200908409J
The North American Nanohertz Observatory for Gravitational Waves
(NANOGrav) project has the primary goal of detecting and characterizing
low-frequency gravitational waves through high-precision pulsar
timing. The mitigation of interstellar effects is crucial to achieve
the necessary precision for gravitational wave detection. Effects
like dispersion and scattering are stronger at lower observing
frequencies, with the variation of these quantities over week-month
timescales requiring high-cadence multifrequency observations for
pulsar timing projects. In this work, we utilize the dual-frequency
observing capability of the Giant Metrewave Radio Telescope (GMRT) and
evaluate the potential decrease in dispersion measure (DM) uncertainties
when combined with existing pulsar timing array data. We present the
timing analysis for four millisecond pulsars observed with the GMRT
simultaneously at 322 and 607 MHz, and compare the DM measurements
with those obtained through NANOGrav observations with the Green Bank
Telescope and Arecibo Observatory at 1400-2300 MHz frequencies. Measured
DM values with the GMRT and NANOGrav program show significant offsets
for some pulsars, which could be caused by pulse profile evolution
between the two frequency bands. In comparison to the predicted DM
uncertainties when incorporating these low-frequency data into the
NANOGrav data set, we find that higher-precision GMRT data is necessary
to provide improved DM measurements. Through the detection and analysis
of pulse profile baseline ripple in data on test pulsar B1929+10,
we find that, while not important for these data, it may be relevant
for other timing data sets. We discuss the possible advantages and
challenges of incorporating GMRT data into NANOGrav and International
Pulsar Timing Array data sets.
Title: Discovery and Timing of Three Millisecond Pulsars in Radio
and Gamma-Rays with the Giant Metrewave Radio Telescope and Fermi
Large Area Telescope
Authors: Bhattacharyya, B.; Roy, J.; Johnson, T. J.; Ray, P. S.;
Freire, P. C. C.; Gupta, Y.; Bhattacharya, D.; Kaninghat, A.; Stappers,
B. W.; Ferrara, E. C.; Sengupta, S.; Rathour, R. S.; Kerr, M.; Smith,
D. A.; Saz Parkinson, P. M.; Ransom, S. M.; Michelson, P. F.
Bibcode: 2021ApJ...910..160B
Altcode: 2021arXiv210204026B
We performed deep observations to search for radio pulsations in
the directions of 375 unassociated Fermi Large Area Telescope γ-ray
sources using the Giant Metrewave Radio Telescope (GMRT) at 322 and
607 MHz. In this paper we report the discovery of three millisecond
pulsars (MSPs), PSR J0248+4230, PSR J1207-5050, and PSR J1536-4948. We
conducted follow-up timing observations for ∼5 yr with the GMRT and
derived phase-coherent timing models for these MSPs. PSR J0248+4230
and J1207-5050 are isolated MSPs having periodicities of 2.60 ms and
4.84 ms. PSR J1536-4948 is a 3.07 ms pulsar in a binary system with an
orbital period of ∼62 days about a companion of a minimum mass of
0.32 M⊙. We also present multifrequency pulse profiles
of these MSPs from the GMRT observations. PSR J1536-4948 is an MSP
with an extremely wide pulse profile having multiple components. Using
the radio timing ephemeris we subsequently detected γ-ray pulsations
from these three MSPs, confirming them as the sources powering the
γ-ray emission. For PSR J1536-4948 we performed combined radio-γ-ray
timing using ∼11.6 yr of γ-ray pulse times of arrival (TOAs) along
with the radio TOAs. PSR J1536-4948 also shows evidence for pulsed
γ-ray emission out to above 25 GeV, confirming earlier associations
of this MSP with a ≥10 GeV point source. The multiwavelength pulse
profiles of all three MSPs offer challenges to models of radio and
γ-ray emission in pulsar magnetospheres.
Title: Discovery of a Gamma-Ray Black Widow Pulsar by GPU-accelerated
Einstein@Home
Authors: Nieder, L.; Clark, C. J.; Kandel, D.; Romani, R. W.; Bassa,
C. G.; Allen, B.; Ashok, A.; Cognard, I.; Fehrmann, H.; Freire, P.;
Karuppusamy, R.; Kramer, M.; Li, D.; Machenschalk, B.; Pan, Z.; Papa,
M. A.; Ransom, S. M.; Ray, P. S.; Roy, J.; Wang, P.; Wu, J.; Aulbert,
C.; Barr, E. D.; Beheshtipour, B.; Behnke, O.; Bhattacharyya, B.;
Breton, R. P.; Camilo, F.; Choquet, C.; Dhillon, V. S.; Ferrara,
E. C.; Guillemot, L.; Hessels, J. W. T.; Kerr, M.; Kwang, S. A.;
Marsh, T. R.; Mickaliger, M. B.; Pleunis, Z.; Pletsch, H. J.; Roberts,
M. S. E.; Sanpa-arsa, S.; Steltner, B.
Bibcode: 2020ApJ...902L..46N
Altcode: 2020arXiv200901513N
We report the discovery of 1.97 ms period gamma-ray pulsations from the
75 minute orbital-period binary pulsar now named PSR J1653-0158. The
associated Fermi Large Area Telescope gamma-ray source 4FGL J1653.6-0158
has long been expected to harbor a binary millisecond pulsar. Despite
the pulsar-like gamma-ray spectrum and candidate optical/X-ray
associations—whose periodic brightness modulations suggested an
orbit—no radio pulsations had been found in many searches. The
pulsar was discovered by directly searching the gamma-ray data using
the GPU-accelerated Einstein@Home distributed volunteer computing
system. The multidimensional parameter space was bounded by positional
and orbital constraints obtained from the optical counterpart. More
sensitive analyses of archival and new radio data using knowledge
of the pulsar timing solution yield very stringent upper limits
on radio emission. Any radio emission is thus either exceptionally
weak, or eclipsed for a large fraction of the time. The pulsar has
one of the three lowest inferred surface magnetic-field strengths
of any known pulsar with Bsurf ≍ 4 × 107
G. The resulting mass function, combined with models of the companion
star's optical light curve and spectra, suggests a pulsar mass ≳2
M⊙. The companion is lightweight with mass ∼0.01
M⊙, and the orbital period is the shortest known for
any rotation-powered binary pulsar. This discovery demonstrates the
Fermi Large Area Telescope's potential to discover extreme pulsars
that would otherwise remain undetected.
Title: Pulse Portraits for 30+ Millisecond Pulsars in Terzan 5
Authors: Schult, L.; Ransom, S.; Pennucci, T.; Roy, J.
Bibcode: 2020AAS...23510225S
Altcode:
The science of pulsar timing is dependent upon pulse times-of-arrival
(TOAs) and their precision, so improving them is of the utmost
importance with regards to the future of pulsar timing science and
Pulsar Timing Arrays (PTAs). The most common method to generate TOAs
is to use a high signal-to-noise ratio (S/N) pulse profile to perform
template matching with folded time-series data. This has worked well
previously, but the advent of new wide-band receivers with larger
fractional bandwidth (Bandwidth/Center Frequency of the band>0.4)
introduces new challenges such as non-negligible profile evolution and
interstellar scattering changes across the band and huge numbers of
frequency-dependent TOAs. Tim Pennucci's PulsePortraiture (Pennucci et
al. 2016; Pennucci & Demorest 2018) code and algorithms allow for
the creation of pulse portraits which are models of the pulse profile
of the pulsar as a function of radio frequency. These portraits can
be used for wideband timing that can mitigate the issues mentioned
and improve TOA precision. I have investigated the merits of using
PulsePortraiture to create high S/N pulse portraits and applied them
to time the millisecond pulsar (MSP) J1646-2142. I then applied this
method to more than 30 MSPs in the globular cluster Terzan 5.
Title: Five new real-time detections of fast radio bursts with UTMOST
Authors: Farah, W.; Flynn, C.; Bailes, M.; Jameson, A.; Bateman, T.;
Campbell-Wilson, D.; Day, C. K.; Deller, A. T.; Green, A. J.; Gupta,
V.; Hunstead, R.; Lower, M. E.; Osłowski, S.; Parthasarathy, A.;
Price, D. C.; Ravi, V.; Shannon, R. M.; Sutherland, A.; Temby, D.;
Krishnan, V. Venkatraman; Caleb, M.; Chang, S. -W.; Cruces, M.; Roy,
J.; Morello, V.; Onken, C. A.; Stappers, B. W.; Webb, S.; Wolf, C.
Bibcode: 2019MNRAS.488.2989F
Altcode: 2019arXiv190502293F; 2019MNRAS.tmp.1717F
We detail a new fast radio burst (FRB) survey with the Molonglo Radio
Telescope, in which six FRBs were detected between 2017 June and
2018 December. By using a real-time FRB detection system, we captured
raw voltages for five of the six events, which allowed for coherent
dedispersion and very high time resolution (10.24 μs) studies of
the bursts. Five of the FRBs show temporal broadening consistent
with interstellar and/or intergalactic scattering, with scattering
time-scales ranging from 0.16 to 29.1 ms. One burst, FRB181017, shows
remarkable temporal structure, with three peaks each separated by 1
ms. We searched for phase-coherence between the leading and trailing
peaks and found none, ruling out lensing scenarios. Based on this
survey, we calculate an all-sky rate at 843 MHz of 98^{+59}_{-39}
events sky-1 d-1 to a fluence limit of 8 Jy ms:
a factor of 7 below the rates estimated from the Parkes and ASKAP
telescopes at 1.4 GHz assuming the ASKAP-derived spectral index α =
-1.6 (Fν ∝ να). Our results suggest that FRB
spectra may turn over below 1 GHz. Optical, radio, and X-ray follow-up
has been made for most of the reported bursts, with no associated
transients found. No repeat bursts were found in the survey.
Title: The GMRT High-resolution Southern Sky Survey for Pulsars and
Transients. II. New Discoveries, Timing, and Polarization Properties
Authors: Bhattacharyya, B.; Roy, J.; Stappers, B. W.; Johnson, T.;
Ilie, C. D.; Lyne, A.; Malenta, M.; Weltevrede, P.; Chengalur, J.;
Cooper, S.; Kaur, B.; Keith, M.; Kerr, M.; Kudale, S.; McLaughlin,
M. A.; Ransom, S. M.; Ray, P. S.
Bibcode: 2019ApJ...881...59B
Altcode: 2019arXiv190609574B
We have been conducting the Giant Metrewave Radio Telescope High
Resolution Southern Sky (GHRSS) survey for the last four years and have
discovered 18 pulsars to date. The GHRSS survey is an off-Galactic-plane
survey at 322 MHz in a region of the sky (decl. range -40° to
-54°) complementary to other ongoing low-frequency surveys. In this
paper we report the discovery of three pulsars (PSRs), J1239-48,
J1516-43, and J1726-52. We also present timing solutions for three
pulsars previously discovered with the GHRSS survey: PSR J2144-5237,
a millisecond pulsar with a period P = 5 ms in a 10 days orbit around
a ≤0.18 M⊙ companion; PSR J1516-43, a mildly recycled P
= 36 ms pulsar in a 228 days orbit with a companion of mass ∼0.4 M
⊙ and the P = 320 ms PSR J0514-4408, which we show is a
source of pulsed γ-ray emission. We also report radio polarimetric
observations of three of the GHRSS discoveries, PSRs J0418-4154,
J0514-4408, and J2144-5237.
Title: The expanded Giant Metrewave Radio Telescope
Authors: Patra, N. N.; Kanekar, N.; Chengalur, J. N.; Sharma, R.; de
Villiers, M.; Ajit Kumar, B.; Bhattacharyya, B.; Bhalerao, V.; Bombale,
R.; Buch, K. D.; Dixit, B.; Ghalame, A.; Gupta, Y.; Hande, P.; Hande,
S.; Hariharan, K.; Kale, R.; Lokhande, S.; Phakatkar, S.; Prajapati,
A.; Rai, S. K.; Raybole, P.; Roy, J.; Shaikh, A. K.; Sureshkumar, S.
Bibcode: 2019MNRAS.483.3007P
Altcode: 2018MNRAS.tmp.3113P; 2019arXiv190100906P
With 30 antennas and a maximum baseline length of 25 km, the Giant
Metrewave Radio Telescope (GMRT) is the premier low-frequency radio
interferometer today. We have carried out a study of possible expansions
of the GMRT, via adding new antennas and installing focal plane arrays
(FPAs), to improve its point-source sensitivity, surface brightness
sensitivity, angular resolution, field of view, and UV coverage. We have
carried out array configuration studies, aimed at minimizing the number
of new GMRT antennas required to obtain a well-behaved synthesized
beam over a wide range of angular resolutions for full-synthesis
observations. This was done via two approaches, tomographic projection
and random sampling, to identify the optimal locations for the new GMRT
antennas. We report results for the optimal locations of the antennas
of an expanded array (the `EGMRT'), consisting of the existing 30 GMRT
antennas, 30 new antennas at short distances, ≲2.5 km from the GMRT
array centre, and 26 additional antennas at relatively long distances,
≈5-25 km from the array centre. The collecting area and the field
of view of the proposed EGMRT array would be larger by factors of,
respectively, ≈3 and ≈30, than those of the GMRT. Indeed, the
EGMRT continuum sensitivity and survey speed with 550-850 MHz FPAs
installed on the 45 antennas within a distance of ≈2.5 km of the array
centre would be far better than those of any existing interferometer,
and comparable to the sensitivity and survey speed of Phase-1 of the
Square Kilometre Array.
Title: LOFT-e: Localisation Of Fast Transients with e-MERLIN
Authors: Walker, C. R. H.; Breton, R. P.; Harrison, P. A.; Holloway,
A.; Keith, M. J.; Kramer, M.; Malenta, M.; Mickaliger, M. B.; Roy,
J.; Scragg, T. W.; Stappers, B. W.
Bibcode: 2018IAUS..337..422W
Altcode: 2018arXiv180401904W
The majority of fast radio bursts (FRBs) are poorly localised,
hindering their potential scientific yield as galactic, intergalactic,
and cosmological probes. LOFT-e, a digital backend for the U.K.'s
e-MERLIN seven-telescope interferometer will provide commensal search
and real-time detection of FRBs, taking full advantage of its field of
view (FoV), sensitivity, and observation time. Upon burst detection,
LOFT-e will store raw data offline, enabling the sub-arcsecond
localisation provided by e-MERLIN and expanding the pool of localised
FRBs. The high-time resolution backend will additionally introduce
pulsar observing capabilities to e-MERLIN.
Title: Pulsar Searches with the SKA
Authors: Levin, L.; Armour, W.; Baffa, C.; Barr, E.; Cooper, S.;
Eatough, R.; Ensor, A.; Giani, E.; Karastergiou, A.; Karuppusamy,
R.; Keith, M.; Kramer, M.; Lyon, R.; Mackintosh, M.; Mickaliger,
M.; van Nieuwpoort, R.; Pearson, M.; Prabu, T.; Roy, J.; Sinnen, O.;
Spitler, L.; Spreeuw, H.; Stappers, B. W.; van Straten, W.; Williams,
C.; Wang, H.; Wiesner, K.; SKA TDT Team
Bibcode: 2018IAUS..337..171L
Altcode: 2017arXiv171201008L
The Square Kilometre Array will be an amazing instrument for pulsar
astronomy. While the full SKA will be sensitive enough to detect all
pulsars in the Galaxy visible from Earth, already with SKA1, pulsar
searches will discover enough pulsars to increase the currently known
population by a factor of four, no doubt including a range of amazing
unknown sources. Real time processing is needed to deal with the 60
PB of pulsar search data collected per day, using a signal processing
pipeline required to perform more than 10 POps. Here we present the
suggested design of the pulsar search engine for the SKA and discuss
challenges and solutions to the pulsar search venture.
Title: Short-timescale γ-Ray Variability in CTA 102
Authors: Shukla, A.; Mannheim, K.; Patel, S. R.; Roy, J.; Chitnis,
V. R.; Dorner, D.; Rao, A. R.; Anupama, G. C.; Wendel, C.
Bibcode: 2018ApJ...854L..26S
Altcode:
The flat-spectrum radio quasar CTA 102 experienced a prolonged state of
enhanced activity across the entire observed electromagnetic spectrum
during 2016-2017, most pronounced during a major outburst between
2016 December and 2017 May. Fermi-LAT observed a flux of (2.2 ± 0.2)
× 10-5 photons cm-2 s-1 at energies
above 100 MeV on 2017 April 19 during a single orbit. We report here the
detection of significant (4.7σ) flux variations down to timescales of
∼5 minutes during this orbit. The measured variability timescale is
much shorter than the light-travel time across the central black hole
(∼70 minutes) indicating a very compact emission region within the
jet, similar to that seen in IC 310, Mrk 501, or PKS 1222+21 from MAGIC
observations. This short-timescale variability is unexpected since
the γ-ray spectrum shows no sign of attenuation due to pair creation
in interactions with photons from the broad emission line region, and
therefore must be assumed to originate far from the black hole. The
observed fast variability could either indicate the dissipation of
magnetic islands or protons in a collimated beam from the base of the
jet encountering the turbulent plasma at the end of the magnetic nozzle.
Title: VizieR Online Data Catalog: Gravitational waves from known
pulsars (Aasi+, 2014)
Authors: Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott,
T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams,
T.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar,
O. D.; Ajith, P.; Allen, B.; Allocca, A.; Ceron, E. A.; Amariutei,
D.; Anderson, R. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.;
Araya, M. C.; Arceneaux, C.; Areeda, J.; Ast, S.; Aston, S. M.;
Astone, P.; Aufmuth, P.; Aulbert, C.; Austin, L.; Aylott, B. E.;
Babak, S.; Baker, P. T.; Ballardin, G.; Ballmer, S. W.; Barayoga,
J. C.; Barker, D.; Barnum, S. H.; Barone, F.; Barr, B.; Barsotti,
L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti,
A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Behnke,
B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.;
Bergmann, G.; Berliner, J. M.; Bersanetti, D.; Bertolini, A.; Bessis,
D.; Betzwieser, J.; Beyersdorf, P. T.; Bhadbhade, T.; Bilenko, I. A.;
Billingsley, G.; Birch, J.; Bitossi, M.; Bizouard, M. A.; Black, E.;
Blackburn, J. K.; Blackburn, L.; Blair, D.; Blom, M.; Bock, O.; Bodiya,
T. P.; Boer, M.; Bogan, C.; Bo, Nd C.; Bondu, F.; Bonelli, L.; Bonnand,
R.; Bork, R.; Born, M.; Boschi, V.; Bose, S.; Bosi, L.; Bowers, J.;
Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brannen,
C. A.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet,
A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown,
D. A.; Brown, D. D.; Bruckner, F.; Bulik, T.; Bulten, H. J.; Buonanno,
A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.;
Calderon Bustillo, J.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon,
K. C.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone,
L.; Caride, S.; Castiglia, A.; Caudill, S.; Cavaglia, M.; Cavalier,
F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty,
R.; Chalermsongsak, T.; Chao, S.; Charlton, P.; Chassande-Mottin, E.;
Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow,
J.; Christensen, N.; Chu, Q.; Chua, S. S. Y.; Chung, S.; Ciani,
G.; Clara, F.; Clark, D. E.; Clark, J. A.; Cleva, F.; Coccia, E.;
Cohadon, P. -F.; Colla, A.; Colombini, M.; Constancio, M. Jr; Conte,
A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.;
Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J. -P.; Countryman,
S.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Craig,
K.; Creighton, J. D. E.; Creighton, T. D.; Crowder, S. G.; Cumming,
A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Dal Canton, T.; Damjanic,
M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.;
Daudert, B.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.;
Day, R.; Dayanga, T.; De Rosa, R.; Debreczeni, G.; Degallaix, J.;
Del Pozzo, W.; Deleeuw, E.; Deleglise, S.; Denker, T.; Dent, T.;
Dereli, H.; Dergachev, V.; Derosa, R.; Desalvo, R.; Dhurandhar, S.;
di Fiore, L.; di Lieto, A.; di Palma, I.; di, Virgilio A.; Diaz,
M.; Dietz, A.; Dmitry, K.; Donovan, F.; Dooley, K. L.; Doravari, S.;
Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J. -C.;
Dwyer, S.; Eberle, T.; Edwards, M.; Effler, A.; Ehrens, P.; Eichholz,
J.; Eikenberry, S. S.; Endroczi, G.; Essick, R.; Etzel, T.; Evans,
K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst,
S.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W.; Favata, M.; Fazi, D.;
Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.;
Finn, L. S.; Fiori, I.; Fisher, R.; Flaminio, R.; Foley, E.; Foley,
S.; Forsi, E.; Fotopoulos, N.; Fournier, J. -D.; Franco, S.; Frasca,
S.; Frasconi, F.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey,
R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fujimoto, M. -K.;
Fulda, P.; Fyffe, M.; Gair, J.; Gammaitoni, L.; Garcia, J.; Garufi,
F.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L.;
Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto,
A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; Goetz, R.;
Gondan, L.; Gonzalez, G.; Gordon, N.; Gorodetsky, M. L.; Gossan,
S.; Gossler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.;
Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson,
A. M.; Griffo, C.; Groot, P.; Grote, H.; Grover, K.; Grunewald, S.;
Guidi, G. M.; Guido, C.; Gushwa, K. E.; Gustafson, E. K.; Gustafson,
R.; Hall, B.; Hall, E.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks,
J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.;
Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Heefner,
J.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.;
Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hild, S.;
Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.;
Horrom, T.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hu, Y.; Hua, Z.;
Huang, V.; Huerta, E. A.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh,
M.; Huynh-Dinh, T.; Iafrate, J.; Ingram, D. R.; Inta, R.; Isogai, T.;
Ivanov, A.; Iyer, B. R.; Izumi, K.; Jacobson, M.; James, E.; Jang,
H.; Jang, Y. J.; Jaranowski, P.; Jimenez-Forteza, F.; Johnson, W. W.;
Jones, D.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; K, H.;
Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.;
Kasprzack, M.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer,
H.; Kaufman, K.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kefelian, F.;
Keitel, D.; Kelley, D. B.; Kells, W.; Keppel, D. G.; Khalaidovski, A.;
Khalili, F. Y.; Khazanov, E. A.; Kim, B. K.; Kim, C.; Kim, K.; Kim,
N.; Kim, W.; Kim, Y. -M.; King, E. J.; King, P. J.; Kinzel, D. L.;
Kissel, J. S.; Klimen, Ko S.; Kline, J.; Koehlenbeck, S.; Kokeyama,
K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak,
D.; Kremin, A.; Kringel, V.; Krishnan, B.; Krolak, A.; Kucharczyk,
C.; Kudla, S.; Kuehn, G.; Kumar, A.; Kumar, P.; Kumar, R.; Kurdyumov,
R.; Kwee, P.; Landry, M.; Lantz, B.; Larson, S.; Lasky, P. D.; Lawrie,
C.; Lazzarini, A.; Le Roux, A.; Leaci, P.; Lebigot, E. O.; Lee, C. -H.;
Lee, H. K.; Lee, H. M.; Lee, J.; Leonardi, M.; Leong, J. R.; Leroy, N.;
Letendre, N.; Levine, B.; Lewis, J. B.; Lhuillier, V.; Li, T. G. F.;
Lin, A. C.; Littenberg, T. B.; Litvine, V.; Liu, F.; Liu, H.; Liu,
Y.; Liu, Z.; Lloyd, D.; Lockerbie, N. A.; Lockett, V.; Lodhia, D.;
Loew, K.; Logue, J.; Lombardi, A. L.; Lorenzini, M.; Loriette, V.;
Lormand, M.; Losurdo, G.; Lough, J.; Luan, J.; Lubinski, M. J.; Luck,
H.; Lundgren, A. P.; MacArthur, J.; MacDonald, E.; Machenschalk,
B.; Macinnis, M.; MacLeod, D. M.; Magana-Sandoval, F.; Mageswaran,
M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man,
N.; Manca, G. M.; Mandel, I.; Mandic, V.; Mangano, V.; Mantovani, M.;
Marchesoni, F.; Marion, F.; Marka, S.; Marka, Z.; Markosyan, A.; Maros,
E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Martinelli,
L.; Martynov, D.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger,
T. J.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.;
May, G.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.;
McGuire, S. C.; McIntyre, G.; McIver, J.; Meacher, D.; Meadors, G. D.;
Mehmet, M.; Meidam, J.; Meier, T.; Melatos, A.; Mendell, G.; Mercer,
R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.;
Mikhailov, E. E.; Milano, L.; Miller, J.; Minenkov, Y.; Mingarelli,
C. M. F.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman,
R.; Moe, B.; Mohan, M.; Mohapatra, S. R. P.; Mokler, F.; Moraru,
D.; Moreno, G.; Morgado, N.; Mori, T.; Morriss, S. R.; Mossavi, K.;
Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee,
S.; Mullavey, A.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.;
Nagy, M. F.; Nanda, Kumar D.; Nardecchia, I.; Nash, T.; Naticchioni,
L.; Nayak, R.; Necula, V.; Nelemans, G.; Neri, I.; Neri, M.; Newton,
G.; Nguyen, T.; Nishida, E.; Nishizawa, A.; Nitz, A.; Nocera, F.;
Nolting, D.; Normandin, M. E.; Nuttall, L. K.; Ochsner, E.; O'Dell, J.;
Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oppermann,
P.; O'Reilly, B.; Ortega Larcher, W.; O'Shaughnessy, R.; Osthelder,
C.; Ottaway, D. J.; Ottens, R. S.; Ou, J.; Overmier, H.; Owen, B. J.;
Padilla, C.; Pai, A.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.;
Paoletti, R.; Papa, M. A.; Paris, H.; Pasqualetti, A.; Passaquieti,
R.; Passuello, D.; Pedraza, M.; Peiris, P.; Penn, S.; Perreca, A.;
Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pierro, V.;
Pinard, L.; Pindor, B.; Pinto, I. M.; Pitkin, M.; Poeld, J.; Poggiani,
R.; Poole, V.; Poux, C.; Predoi, V.; Prestegard, T.; Price, L. R.;
Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.;
Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.;
Quintero, E.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Racz,
I.; Radkins, H.; Raffai, P.; Raja, S.; Rajalakshmi, G.; Rakhmanov,
M.; Ramet, C.; Rapagnani, P.; Raymond, V.; Re, V.; Reed, C. M.;
Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen,
R.; Riles, K.; Robertson, N. A.; Robinet, F.; Rocchi, A.; Roddy, S.;
Rodriguez, C.; Rodruck, M.; Roever, C.; Rolland, L.; Rollins, J. G.;
Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosinska, D.;
Rowan, S.; Rudiger, A.; Ruggi, P.; Ryan, K.; Salemi, F.; Sammut, L.;
Sandberg, V.; Sanders, J.; Sannibale, V.; Santiago-Prieto, I.; Saracco,
E.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R.;
Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schreiber, E.;
Schuette, D.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.;
Scott, S. M.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Sentenac, D.;
Sergeev, A.; Shaddock, D.; Shah, S.; Shahriar, M. S.; Shaltev, M.;
Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siellez,
K.; Siemens, X.; Sigg, D.; Simakov, D.; Singer, A.; Singer, L.; Sintes,
A. M.; Skelton, G. R.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.;
Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Soden, K.; Son,
E. J.; Sorazu, B.; Souradeep, T.; Sperandio, L.; Staley, A.; Steinert,
E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stevens,
D.; Stochino, A.; Stone, R.; Strain, K. A.; Straniero, N.; Strigin,
S.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.;
Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szeifert, G.; Tacca, M.;
Talukder, D.; Tang, L.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.;
Ter Braack, A. P. M.; Thirugnanasambandam, M. P.; Thomas, M.; Thomas,
P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, V.; Tokmakov,
K. V.; Tomlinson, C.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres,
C. V.; Torrie, C. I.; Travasso, F.; Traylor, G.; Tse, M.; Ugolini,
D.; Unnikrishnan, C. S.; Vahlbruch, H.; Vajente, G.; Vallisneri,
M.; van den Brand, J. F. J.; van den Broeck, C.; van der Putten, S.;
van der Sluys, M. V.; van Heijningen, J.; van Veggel, A. A.; Vass,
S.; Vasuth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.;
Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Verma, S.; Vetrano,
F.; Vicere, A.; Vincent-Finley, R.; Vinet, J. -Y.; Vitale, S.; Vlcek,
B.; Vo, T.; Vocca, H.; Vorvick, C.; Vousden, W. D.; Vrinceanu, D.;
Vyachanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Waldman, S. J.;
Walker, M.; Wallace, L.; Wan, Y.; Wang, J.; Wang, M.; Wang, X.;
Wanner, A.; Ward, R. L.; Was, M.; Weaver, B.; Wei, L. -W.; Weinert,
M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.;
West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.;
White, D. J.; Whiting, B. F.; Wibowo, S.; Wiesner, K.; Wilkinson,
C.; Williams, L.; Williams, R.; Williams, T.; Willis, J. L.; Willke,
B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wittel, H.;
Woan, G.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yancey,
C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yum, H.; Yvert, M.;
Zadrozny, A.; Zanolin, M.; Zendri, J. -P.; Zhang, F.; Zhang, L.;
Zhao, C.; Zhu, H.; Zhu, X. J.; Zotov, N.; Zucker, M. E.; Zweizig,
J.; Buchner, S.; Cognard, I.; Corongiu, A.; D'Amico, N.; Espinoza,
C. M.; Freire, P. C. C.; Gotthelf, E. V.; Guillemot, L.; Hessels,
J. W. T.; Hobbs, G. B.; Kramer, M.; Lyne, A. G.; Marshall, F. E.;
Possenti, A.; Ransom, S. M.; Ray, P. S.; Roy, J.; Stappers, B. W.;
VIRGO Collaboration
Bibcode: 2017yCat..17850119A
Altcode:
In this paper we have used calibrated data from the Virgo second
(Aasi et al. 2012CQGra..29o5002A) and fourth science runs (VSR2 and
VSR4) and the LIGO sixth science run (S6). Virgo's third science run
(VSR3) was relatively insensitive in comparison with VSR4 and has
not been included in this analysis. This was partially because Virgo
introduced monolithic mirror suspensions prior to VSR4 which improved
sensitivity in the low-frequency range. During S6, the two LIGO 4 km
detectors at Hanford, Washington (LHO/H1), and Livingston, Louisiana
(LLO/L1), were running in an enhanced configuration (Adhikari et
al. 2006, Enhanced LIGO, Tech. Rep. LIGO-T060156-v01, California
Institute of Technology, Massachusetts Institute of Technology,
https://dcc.ligo.org/LIGO-T060156-v1/public) over that from the previous
S5 run (Abbott et al. 2009RPPh...72g6901A). (1 data file).
Title: A Question and Answer Guide to Astronomy
Authors: Christian, Carol; Roy, Jean-René
Bibcode: 2017qaga.book.....C
Altcode:
Preface; 1. The sky viewed from Earth; 2. The Earth and Moon system;
3. The Solar System; 4. Stars and stellar systems; 5. Galaxies and the
Universe; 6. Life in the Universe; 7. Amateur astronomy; 8. Telescopes
and instruments; Unit conversion and basic physical and astronomical
measurements; References; Bibliography; Index.
Title: Detection of Very Hard γ-Ray Spectrum from the TeV Blazar
Mrk 501
Authors: Shukla, A.; Mannheim, K.; Chitnis, V. R.; Roy, J.; Acharya,
B. S.; Dorner, D.; Hughes, G.; Biland, A.
Bibcode: 2016ApJ...832..177S
Altcode:
The occasional hardening of the GeV-to-TeV spectrum observed from
the blazar Mrk 501 has reopened the debate on the physical origin of
radiation and particle acceleration processes in TeV blazars. We have
used the ∼7 years of Fermi-LAT data to search for the time intervals
with unusually hard spectra from the nearby TeV blazar Mrk 501. We
detected hard spectral components above 10 GeV with photon index
<1.5 at a significance level of more than 5 sigma on 17 occasions,
each with 30 day integration time. The photon index of the hardest
component reached a value of 0.89 ± 0.29. We interpret these hard
spectra as signatures of intermittent injection of sharply peaked and
localized particle distributions from the base of the jet.
Title: Performance of large area x-ray proportional counters in a
balloon experiment
Authors: Roy, J.; Agrawal, P. C.; Dedhia, D. K.; Manchanda, R. K.;
Shah, P. B.; Chitnis, V. R.; Gujar, V. M.; Parmar, J. V.; Pawar,
D. M.; Kurhade, V. B.
Bibcode: 2016ExA....42..249R
Altcode: 2016ExA...tmp...18R; 2016arXiv160903531R
ASTROSAT is India's first satellite fully devoted to astronomical
observations covering a wide spectral band from optical to hard X-rays
by a complement of 4 co-aligned instruments and a Scanning Sky X-ray
Monitor. One of the instruments is Large Area X-ray Proportional Counter
with 3 identical detectors. In order to assess the performance of this
instrument, a balloon experiment with two prototype Large Area X-ray
Proportional Counters (LAXPC) was carried out on 2008 April 14. The
design of these LAXPCs was similar to those on the ASTROSAT except that
their field of view (FOV) was 3 ∘ × 3 ∘
versus FOV of 1 ∘ × 1 ∘ for the LAXPCs on
the ASTROSAT. The LAXPCs are aimed at the timing and spectral studies
of X-ray sources in 3-80 keV region. In the balloon experiment, the
LAXPC, associated electronics and support systems were mounted on an
oriented platform which could be pre-programmed to track any source
in the sky. A brief description of the LAXPC design, laboratory
tests, calibration and the detector characteristics is presented
here. The details of the experiment and background counting rates of
the 2 LAXPCs at the float altitude of about 41 km are presented in
different energy bands. The bright black hole X-ray binary Cygnus X-1
(Cyg X-1) was observed in the experiment for ∼ 3 hours. Details of
Cyg X-1 observations, count rates measured from it in different energy
intervals and the intensity variations of Cyg X-1 detected during the
observations are presented and briefly discussed.
Title: Single-Source Gravitational Wave Limits From the J1713+0747
24-hr Global Campaign
Authors: Dolch, T.; NANOGrav Collaboration; Ellis, J. A.; Chatterjee,
S.; Cordes, J. M.; Lam, M. T.; Bassa, C.; Bhattacharyya, B.; Champion,
D. J.; Cognard, I.; Crowter, K.; Demorest, P. B.; Hessels, J. W. T.;
Janssen, G.; Jenet, F. A.; Jones, G.; Jordan, C.; Karuppusamy, R.;
Keith, M.; Kondratiev, V. I.; Kramer, M.; Lazarus, P.; Lazio, T. J. W.;
Lorimer, D. R.; Madison, D. R.; McLaughlin, M. A.; Palliyaguru,
N.; Perrodin, D.; Ransom, S. M.; Roy, J.; Shannon, R. M.; Smits,
R.; Stairs, I. H.; Stappers, B. W.; Stinebring, D. R.; Stovall, K.;
Verbiest, J. P. W.; Zhu, W. W.
Bibcode: 2016JPhCS.716a2014D
Altcode: 2015arXiv150905446D
Dense, continuous pulsar timing observations over a 24-hr period
provide a method for probing intermediate gravitational wave (GW)
frequencies from 10 microhertz to 20 millihertz. The European Pulsar
Timing Array (EPTA), the North American Nanohertz Observatory for
Gravitational Waves (NANOGrav), the Parkes Pulsar Timing Array (PPTA),
and the combined International Pulsar Timing Array (IPTA) all use
millisecond pulsar observations to detect or constrain GWs typically
at nanohertz frequencies. In the case of the IPTA's nine-telescope
24-Hour Global Campaign on millisecond pulsar J1713+0747, GW limits
in the intermediate frequency regime can be produced. The negligible
change in dispersion measure during the observation minimizes red noise
in the timing residuals, constraining any contributions from GWs due
to individual sources. At 10-5 Hz, the 95% upper limit on
strain is 10-11 for GW sources in the pulsar's direction.
Title: The GMRT High Resolution Southern Sky Survey for Pulsars and
Transients. I. Survey Description and Initial Discoveries
Authors: Bhattacharyya, B.; Cooper, S.; Malenta, M.; Roy, J.;
Chengalur, J.; Keith, M.; Kudale, S.; McLaughlin, M.; Ransom, S. M.;
Ray, P. S.; Stappers, B. W.
Bibcode: 2016ApJ...817..130B
Altcode: 2015arXiv150907177B
We are conducting a survey for pulsars and transients using the
Giant Metrewave Radio Telescope (GMRT). The GMRT High Resolution
Southern Sky (GHRSS) survey is an off-Galactic plane (| b| >
5) survey in the declination range -40° to -54° at 322 MHz. With
the high time (up to 30.72 μs) and frequency (up to 0.016275 MHz)
resolution observing modes, the 5σ detection limit is 0.5 mJy for
a 2 ms pulsar with a 10% duty cycle at 322 MHz. The total GHRSS sky
coverage of 2866 deg2 will result from 1953 pointings,
each covering 1.8 deg2. The 10σ detection limit for a
5 ms transient burst is 1.6 Jy for the GHRSS survey. In addition,
the GHRSS survey can reveal transient events like rotating radio
transients or fast radio bursts. With 35% of the survey completed
(I.e., 1000 deg2), we report the discovery of 10 pulsars,
1 of which is a millisecond pulsar (MSP), which is among the highest
pulsar per square degree discovery rates for any off-Galactic plane
survey. We re-detected 23 known in-beam pulsars. Utilizing the imaging
capability of the GMRT, we also localized four of the GHRSS pulsars
(including the MSP) in the gated image plane within ±10″. We
demonstrated rapid convergence in pulsar timing with a more precise
position than is possible with single-dish discoveries. We also show
that we can localize the brightest transient sources with simultaneously
obtained lower time resolution imaging data, demonstrating a technique
that may have application in the Square Kilometre Array.
Title: Discovery of Gamma-Ray Pulsations from the Transitional
Redback PSR J1227-4853
Authors: Johnson, T. J.; Ray, P. S.; Roy, J.; Cheung, C. C.; Harding,
A. K.; Pletsch, H. J.; Fort, S.; Camilo, F.; Deneva, J.; Bhattacharyya,
B.; Stappers, B. W.; Kerr, M.
Bibcode: 2015ApJ...806...91J
Altcode: 2015arXiv150206862J
The 1.69 ms spin period of PSR J1227-4853 was recently discovered in
radio observations of the low-mass X-ray binary XSS J12270-4859
following the announcement of a possible transition to a
rotation-powered millisecond pulsar state, inferred from decreases
in optical, X-ray, and gamma-ray flux from the source. We report
the detection of significant (5σ) gamma-ray pulsations after the
transition, at the known spin period, using ∼1 year of data from
the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space
Telescope. The gamma-ray light curve of PSR J1227-4853 can be fit by
one broad peak, which occurs at nearly the same phase as the main peak
in the 1.4 GHz radio profile. The partial alignment of light-curve
peaks in different wavebands suggests that at least some of the radio
emission may originate at high altitude in the pulsar magnetosphere, in
extended regions co-located with the gamma-ray emission site. We folded
the LAT data at the orbital period, both pre- and post-transition,
but find no evidence for significant modulation of the gamma-ray
flux. Analysis of the gamma-ray flux over the mission suggests an
approximate transition time of 2012 November 30. Continued study
of the pulsed emission and monitoring of PSR J1227-4853, and other
known redback systems, for subsequent flux changes will increase our
knowledge of the pulsar emission mechanism and transitioning systems.
Title: A 24 Hr Global Campaign to Assess Precision Timing of the
Millisecond Pulsar J1713+0747
Authors: Dolch, T.; Lam, M. T.; Cordes, J.; Chatterjee, S.; Bassa,
C.; Bhattacharyya, B.; Champion, D. J.; Cognard, I.; Crowter, K.;
Demorest, P. B.; Hessels, J. W. T.; Janssen, G.; Jenet, F. A.; Jones,
G.; Jordan, C.; Karuppusamy, R.; Keith, M.; Kondratiev, V.; Kramer,
M.; Lazarus, P.; Lazio, T. J. W.; Lee, K. J.; McLaughlin, M. A.;
Roy, J.; Shannon, R. M.; Stairs, I.; Stovall, K.; Verbiest, J. P. W.;
Madison, D. R.; Palliyaguru, N.; Perrodin, D.; Ransom, S.; Stappers,
B.; Zhu, W. W.; Dai, S.; Desvignes, G.; Guillemot, L.; Liu, K.; Lyne,
A.; Perera, B. B. P.; Petroff, E.; Rankin, J. M.; Smits, R.
Bibcode: 2014ApJ...794...21D
Altcode: 2014arXiv1408.1694D
The radio millisecond pulsar J1713+0747 is regarded as one of the
highest-precision clocks in the sky and is regularly timed for the
purpose of detecting gravitational waves. The International Pulsar
Timing Array Collaboration undertook a 24 hr global observation of
PSR J1713+0747 in an effort to better quantify sources of timing
noise in this pulsar, particularly on intermediate (1-24 hr)
timescales. We observed the pulsar continuously over 24 hr with
the Arecibo, Effelsberg, GMRT, Green Bank, LOFAR, Lovell, Nançay,
Parkes, and WSRT radio telescopes. The combined pulse times-of-arrival
presented here provide an estimate of what sources of timing noise,
excluding DM variations, would be present as compared to an idealized
\sqrt{N} improvement in timing precision, where N is the number of
pulses analyzed. In the case of this particular pulsar, we find that
intrinsic pulse phase jitter dominates arrival time precision when the
signal-to-noise ratio of single pulses exceeds unity, as measured using
the eight telescopes that observed at L band/1.4 GHz. We present first
results of specific phenomena probed on the unusually long timescale
(for a single continuous observing session) of tens of hours, in
particular interstellar scintillation, and discuss the degree to which
scintillation and profile evolution affect precision timing. This
paper presents the data set as a basis for future, deeper studies.
Title: Gravitational Waves from Known Pulsars: Results from the
Initial Detector Era
Authors: Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T.;
Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.;
Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.;
Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.;
Anderson, R. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya,
M. C.; Arceneaux, C.; Areeda, J.; Ast, S.; Aston, S. M.; Astone,
P.; Aufmuth, P.; Aulbert, C.; Austin, L.; Aylott, B. E.; Babak, S.;
Baker, P. T.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barker,
D.; Barnum, S. H.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia,
M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J.;
Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Behnke, B.; Bejger,
M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Bergmann,
G.; Berliner, J. M.; Bersanetti, D.; Bertolini, A.; Bessis, D.;
Betzwieser, J.; Beyersdorf, P. T.; Bhadbhade, T.; Bilenko, I. A.;
Billingsley, G.; Birch, J.; Bitossi, M.; Bizouard, M. A.; Black,
E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Blom, M.; Bock, O.;
Bodiya, T. P.; Boer, M.; Bogan, C.; Bond, C.; Bondu, F.; Bonelli,
L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, S.; Bosi,
L.; Bowers, J.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.;
Branchesi, M.; Brannen, C. A.; Brau, J. E.; Breyer, J.; Briant, T.;
Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger,
M.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brückner, F.; Bulik,
T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.;
Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp,
J. B.; Campsie, P.; Cannon, K. C.; Canuel, B.; Cao, J.; Capano, C. D.;
Carbognani, F.; Carbone, L.; Caride, S.; Castiglia, A.; Caudill, S.;
Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.;
Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chao, S.; Charlton,
P.; Chassande-Mottin, E.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo,
A.; Cho, H. S.; Chow, J.; Christensen, N.; Chu, Q.; Chua, S. S. Y.;
Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Cleva,
F.; Coccia, E.; Cohadon, P. -F.; Colla, A.; Colombini, M.; Constancio,
M., Jr.; Conte, A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.;
Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J. -P.;
Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.;
Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Crowder, S. G.;
Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Dal Canton, T.;
Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo,
V.; Daudert, B.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.;
Day, R.; Dayanga, T.; De Rosa, R.; Debreczeni, G.; Degallaix, J.;
Del Pozzo, W.; Deleeuw, E.; Deléglise, S.; Denker, T.; Dent, T.;
Dereli, H.; Dergachev, V.; DeRosa, R.; DeSalvo, R.; Dhurandhar, S.;
Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Díaz,
M.; Dietz, A.; Dmitry, K.; Donovan, F.; Dooley, K. L.; Doravari, S.;
Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J. -C.;
Dwyer, S.; Eberle, T.; Edwards, M.; Effler, A.; Ehrens, P.; Eichholz,
J.; Eikenberry, S. S.; Endrőczi, G.; Essick, R.; Etzel, T.; Evans,
K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst,
S.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W.; Favata, M.; Fazi, D.;
Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.;
Finn, L. S.; Fiori, I.; Fisher, R.; Flaminio, R.; Foley, E.; Foley,
S.; Forsi, E.; Fotopoulos, N.; Fournier, J. -D.; Franco, S.; Frasca,
S.; Frasconi, F.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey,
R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fujimoto, M. -K.;
Fulda, P.; Fyffe, M.; Gair, J.; Gammaitoni, L.; Garcia, J.; Garufi,
F.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L.;
Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto,
A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; Goetz, R.;
Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan,
S.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.;
Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson,
A. M.; Griffo, C.; Groot, P.; Grote, H.; Grover, K.; Grunewald, S.;
Guidi, G. M.; Guido, C.; Gushwa, K. E.; Gustafson, E. K.; Gustafson,
R.; Hall, B.; Hall, E.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks,
J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.;
Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Heefner,
J.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.;
Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hild, S.;
Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.;
Horrom, T.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hu, Y.; Hua, Z.;
Huang, V.; Huerta, E. A.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh,
M.; Huynh-Dinh, T.; Iafrate, J.; Ingram, D. R.; Inta, R.; Isogai, T.;
Ivanov, A.; Iyer, B. R.; Izumi, K.; Jacobson, M.; James, E.; Jang,
H.; Jang, Y. J.; Jaranowski, P.; Jiménez-Forteza, F.; Johnson, W. W.;
Jones, D.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; K, Haris;
Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.;
Kasprzack, M.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer,
H.; Kaufman, K.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kéfélian, F.;
Keitel, D.; Kelley, D. B.; Kells, W.; Keppel, D. G.; Khalaidovski, A.;
Khalili, F. Y.; Khazanov, E. A.; Kim, B. K.; Kim, C.; Kim, K.; Kim,
N.; Kim, W.; Kim, Y. -M.; King, E. J.; King, P. J.; Kinzel, D. L.;
Kissel, J. S.; Klimenko, S.; Kline, J.; Koehlenbeck, S.; Kokeyama,
K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak,
D.; Kremin, A.; Kringel, V.; Krishnan, B.; Królak, A.; Kucharczyk,
C.; Kudla, S.; Kuehn, G.; Kumar, A.; Kumar, P.; Kumar, R.; Kurdyumov,
R.; Kwee, P.; Landry, M.; Lantz, B.; Larson, S.; Lasky, P. D.; Lawrie,
C.; Lazzarini, A.; Le Roux, A.; Leaci, P.; Lebigot, E. O.; Lee, C. -H.;
Lee, H. K.; Lee, H. M.; Lee, J.; Lee, J.; Leonardi, M.; Leong, J. R.;
Leroy, N.; Letendre, N.; Levine, B.; Lewis, J. B.; Lhuillier, V.; Li,
T. G. F.; Lin, A. C.; Littenberg, T. B.; Litvine, V.; Liu, F.; Liu,
H.; Liu, Y.; Liu, Z.; Lloyd, D.; Lockerbie, N. A.; Lockett, V.; Lodhia,
D.; Loew, K.; Logue, J.; Lombardi, A. L.; Lorenzini, M.; Loriette, V.;
Lormand, M.; Losurdo, G.; Lough, J.; Luan, J.; Lubinski, M. J.; Lück,
H.; Lundgren, A. P.; Macarthur, J.; Macdonald, E.; Machenschalk, B.;
MacInnis, M.; Macleod, D. M.; Magana-Sandoval, F.; Mageswaran, M.;
Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.;
Manca, G. M.; Mandel, I.; Mandic, V.; Mangano, V.; Mantovani, M.;
Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.;
Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.;
Martinelli, L.; Martynov, D.; Marx, J. N.; Mason, K.; Masserot, A.;
Massinger, T. J.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala,
N.; May, G.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland,
D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; Meacher, D.; Meadors,
G. D.; Mehmet, M.; Meidam, J.; Meier, T.; Melatos, A.; Mendell, G.;
Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.;
Michel, C.; Mikhailov, E. E.; Milano, L.; Miller, J.; Minenkov, Y.;
Mingarelli, C. M. F.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher,
G.; Mittleman, R.; Moe, B.; Mohan, M.; Mohapatra, S. R. P.; Mokler,
F.; Moraru, D.; Moreno, G.; Morgado, N.; Mori, T.; Morriss, S. R.;
Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller,
G.; Mukherjee, S.; Mullavey, A.; Munch, J.; Murphy, D.; Murray, P. G.;
Mytidis, A.; Nagy, M. F.; Nanda Kumar, D.; Nardecchia, I.; Nash, T.;
Naticchioni, L.; Nayak, R.; Necula, V.; Nelemans, G.; Neri, I.; Neri,
M.; Newton, G.; Nguyen, T.; Nishida, E.; Nishizawa, A.; Nitz, A.;
Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L. K.; Ochsner,
E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme,
F.; Oppermann, P.; O'Reilly, B.; Ortega Larcher, W.; O'Shaughnessy,
R.; Osthelder, C.; Ottaway, D. J.; Ottens, R. S.; Ou, J.; Overmier,
H.; Owen, B. J.; Padilla, C.; Pai, A.; Palomba, C.; Pan, Y.; Pankow,
C.; Paoletti, F.; Paoletti, R.; Papa, M. A.; Paris, H.; Pasqualetti,
A.; Passaquieti, R.; Passuello, D.; Pedraza, M.; Peiris, P.; Penn, S.;
Perreca, A.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni,
F.; Pierro, V.; Pinard, L.; Pindor, B.; Pinto, I. M.; Pitkin, M.;
Poeld, J.; Poggiani, R.; Poole, V.; Poux, C.; Predoi, V.; Prestegard,
T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix,
R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo,
P.; Quetschke, V.; Quintero, E.; Quitzow-James, R.; Raab, F. J.;
Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Raja, S.;
Rajalakshmi, G.; Rakhmanov, M.; Ramet, C.; Rapagnani, P.; Raymond,
V.; Re, V.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze,
D. H.; Ricci, F.; Riesen, R.; Riles, K.; Robertson, N. A.; Robinet,
F.; Rocchi, A.; Roddy, S.; Rodriguez, C.; Rodruck, M.; Roever, C.;
Rolland, L.; Rollins, J. G.; Romano, J. D.; Romano, R.; Romanov, G.;
Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan,
K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sanders, J.; Sannibale, V.;
Santiago-Prieto, I.; Saracco, E.; Sassolas, B.; Sathyaprakash, B. S.;
Saulson, P. R.; Savage, R.; Schilling, R.; Schnabel, R.; Schofield,
R. M. S.; Schreiber, E.; Schuette, D.; Schulz, B.; Schutz, B. F.;
Schwinberg, P.; Scott, J.; Scott, S. M.; Seifert, F.; Sellers, D.;
Sengupta, A. S.; Sentenac, D.; Sergeev, A.; Shaddock, D.; Shah, S.;
Shahriar, M. S.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker,
D. H.; Sidery, T. L.; Siellez, K.; Siemens, X.; Sigg, D.; Simakov,
D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G. R.; Slagmolen,
B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.;
Smith-Lefebvre, N. D.; Soden, K.; Son, E. J.; Sorazu, B.; Souradeep,
T.; Sperandio, L.; Staley, A.; Steinert, E.; Steinlechner, J.;
Steinlechner, S.; Steplewski, S.; Stevens, D.; Stochino, A.; Stone,
R.; Strain, K. A.; Straniero, N.; Strigin, S.; Stroeer, A. S.; Sturani,
R.; Stuver, A. L.; Summerscales, T. Z.; Susmithan, S.; Sutton, P. J.;
Swinkels, B.; Szeifert, G.; Tacca, M.; Talukder, D.; Tang, L.;
Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; ter Braack, A. P. M.;
Thirugnanasambandam, M. P.; Thomas, M.; Thomas, P.; Thorne, K. A.;
Thorne, K. S.; Thrane, E.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.;
Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C. V.; Torrie, C. I.;
Travasso, F.; Traylor, G.; Tse, M.; Ugolini, D.; Unnikrishnan, C. S.;
Vahlbruch, H.; Vajente, G.; Vallisneri, M.; van den Brand, J. F. J.;
Van Den Broeck, C.; van der Putten, S.; van der Sluys, M. V.; van
Heijningen, J.; van Veggel, A. A.; Vass, S.; Vasúth, M.; Vaulin, R.;
Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.;
Verkindt, D.; Verma, S.; Vetrano, F.; Viceré, A.; Vincent-Finley, R.;
Vinet, J. -Y.; Vitale, S.; Vlcek, B.; Vo, T.; Vocca, H.; Vorvick, C.;
Vousden, W. D.; Vrinceanu, D.; Vyachanin, S. P.; Wade, A.; Wade, L.;
Wade, M.; Waldman, S. J.; Walker, M.; Wallace, L.; Wan, Y.; Wang, J.;
Wang, M.; Wang, X.; Wanner, A.; Ward, R. L.; Was, M.; Weaver, B.; Wei,
L. -W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen,
L.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.;
Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Wibowo, S.; Wiesner,
K.; Wilkinson, C.; Williams, L.; Williams, R.; Williams, T.; Willis,
J. L.; Willke, B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf,
C. C.; Wittel, H.; Woan, G.; Worden, J.; Yablon, J.; Yakushin, I.;
Yamamoto, H.; Yancey, C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida,
S.; Yum, H.; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zendri, J. -P.;
Zhang, F.; Zhang, L.; Zhao, C.; Zhu, H.; Zhu, X. J.; Zotov, N.; Zucker,
M. E.; Zweizig, J.; Buchner, S.; Cognard, I.; Corongiu, A.; D'Amico,
N.; Espinoza, C. M.; Freire, P. C. C.; Gotthelf, E. V.; Guillemot, L.;
Hessels, J. W. T.; Hobbs, G. B.; Kramer, M.; Lyne, A. G.; Marshall,
F. E.; Possenti, A.; Ransom, S. M.; Ray, P. S.; Roy, J.; Stappers,
B. W.; LIGO Scientific Collaboration; Virgo Collaboration
Bibcode: 2014ApJ...785..119A
Altcode: 2013arXiv1309.4027A
We present the results of searches for gravitational waves from
a large selection of pulsars using data from the most recent
science runs (S6, VSR2 and VSR4) of the initial generation of
interferometric gravitational wave detectors LIGO (Laser Interferometric
Gravitational-wave Observatory) and Virgo. We do not see evidence
for gravitational wave emission from any of the targeted sources
but produce upper limits on the emission amplitude. We highlight the
results from seven young pulsars with large spin-down luminosities. We
reach within a factor of five of the canonical spin-down limit for
all seven of these, whilst for the Crab and Vela pulsars we further
surpass their spin-down limits. We present new or updated limits for
172 other pulsars (including both young and millisecond pulsars). Now
that the detectors are undergoing major upgrades, and, for completeness,
we bring together all of the most up-to-date results from all pulsars
searched for during the operations of the first-generation LIGO, Virgo
and GEO600 detectors. This gives a total of 195 pulsars including the
most recent results described in this paper.
Title: GMRT discovery of a 1.69 ms radio pulsar associated with
XSS J12270-4859
Authors: Roy, J.; Bhattacharyya, B.; Ray, P. S.
Bibcode: 2014ATel.5890....1R
Altcode:
Following the reported state change observed in the low-mass X-ray
binary XSS J12270-4859 (ATel #5647; Bassa et al. 2014, arXiv:1402.0765),
we were granted Director's Discretionary Time to search for radio
pulsations using the GMRT. We observed at 607 MHz with the GMRT coherent
phased-array mode utilizing 70% of the array resulting in a beam width
of 30 arcsec. We recorded 3 scans, each of 1-hour beginning on 2014
Feb 12 at 20:46:15 UTC, producing filter-bank outputs of 512 x 0.0651
MHz sampled at 61.44 microsec.
Title: A Day in the Life of Millisecond Pulsar J1713+0747: Limits
on Timing Precision Over 24 Hours and Implications for Gravitational
Wave Detection
Authors: Dolch, Timothy; Bailes, M.; Bassa, C.; Bhat, R.;
Bhattacharyya, B.; Champion, D.; Chatterjee, S.; Cognard, I.; Cordes,
J. M.; Crowter, K.; Demorest, P.; Finn, L. S.; Fonseca, E.; Hessels,
J.; Hobbs, G.; Janssen, G.; Jones, G.; Jordan, C.; Karuppusamy, R.;
Keith, M.; Kramer, M.; Kraus, A.; Lam, M. T.; Lazarus, P.; Lazio,
J.; Lee, K.; Levin, L.; Liu, K.; Lorimer, D.; Manchester, R. N.;
McLaughlin, M.; Palliyaguru, N.; Perrodin, D.; Petroff, E.; Rajwade,
K.; Rankin, J. M.; Ransom, S. M.; Rosenblum, J.; Roy, J.; Shannon, R.;
Stappers, B.; Stinebring, D.; Stovall, K.; Teixeira, M.; van Leeuwen,
J.; van Straten, W.; Verbiest, J.; Zhu, W.
Bibcode: 2014AAS...22311404D
Altcode:
A 24-hour global observation of millisecond radio pulsar J1713+0747 was
undertaken by the International Pulsar Timing Array (IPTA) collaboration
as an effort to better quantify sources of noise in this object,
which is regularly timed for the purpose of detecting gravitational
waves (GWs). Given an 8-year timing RMS of 30ns, it is regarded as one
of the best precision clocks in the PTA. However, sources of timing
noise visible on timescales longer than the usual 20-30min biweekly
observation may nonetheless be present. Data from the campaign were
taken contiguously with the Parkes, Arecibo, Green Bank, GMRT, LOFAR,
Effelsberg, WSRT, Lovell, and Nancay radio telescopes. The combined
pulse times-of-arrival provide an estimate of the absolute noise floor,
in other words, what unaccounted sources of timing noise impede an
otherwise simple sqrt(N) improvement in timing precision, where N
is the number of pulses in a single observing session. We present
first results of specific phenomena probed on the unusual timescale
of tens of hours, in particular interstellar scattering (ISS), and
discuss the degree to which ISS affects precision timing. Finally,
we examine single pulse information during selected portions of the
observation and determine the degree to which the pulse jitter of
J1713+0747 varies throughout the course of the day-long dataset.
Title: Discovery of the radio and gamma-ray pulsar PSR J2339-0533
associated with the Fermi LAT bright source 0FGL J2339.8-0530
Authors: Ray, Paul S.; Belfiore, A. M.; Saz Parkinson, P.;
Polisensky, E.; Ransom, S. M.; Romani, R. W.; Hessels, J.; Razzano,
M.; Bhattacharyya, B.; Roy, J.; Cognard, I.; Pulsar Search Consortium,
Fermi
Bibcode: 2014AAS...22314007R
Altcode:
We report the detection of radio and gamma-ray pulsations from the
bright Fermi LAT source 0FGL J2339.8-0530. This source was one of
the bright gamma-ray sources uncovered in the first 3 months of
Fermi LAT survey mode observations. Deep X-ray and optical follow up
observations led to the identification of the probable counterpart
that showed all the characteristics of a millisecond pulsar in a 4.6
hour binary orbit, except for pulsations. We have discovered 2.88 ms
radio pulsations in an observation with the NRAO Green Bank Telescope
at 820 MHz, confirming this source as a pulsar and demonstrating
that the companion was substantially more massive than models of the
optical light curve had suggested. With the pulse period and orbital
parameters highly constrained, we were then able to discover the
gamma-ray pulsations in the LAT data, confirming the identification
with 0FGL J2339.8-0530. Detailed timing of the pulsar using the LAT
data provided a measurement of the spin down rate, showing that this
is an energetic millisecond pulsar with spin down luminosity 2.3E34
erg/s. We discuss the improvement in our understanding of the system as
a result of the radio and gamma-ray pulsation discoveries. The Fermi
LAT Collaboration acknowledges support from a number of agencies and
institutes for both development and the operation of the LAT as well
as scientific data analysis. These include NASA and DOE in the United
States, CEA/Irfu and IN2P3/CNRS in France, ASI and INFN in Italy, MEXT,
KEK, and JAXA in Japan, and the K. A. Wallenberg Foundation, the Swedish
Research Council and the National Space Board in Sweden. Additional
support from INAF in Italy and CNES in France for science analysis
during the operations phase is also gratefully acknowledged.
Title: VizieR Online Data Catalog: 2nd Fermi LAT cat. of gamma-ray
pulsars (2PC) (Abdo+, 2013)
Authors: Abdo, A. A.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet,
J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Belfiore, A.;
Bellazzini, R.; Bhattacharyya, B.; Bissaldi, E.; Bloom, E. D.;
Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida,
M.; Bruel, P.; Buehler, R.; Burgay, M.; Burnett, T. H.; Busetto, G.;
Buson, S.; Caliandro, G. A.; Cameron, R. A.; Camilo, F.; Caraveo,
P. A.; Casandjian, J. M.; Cecchi, C.; Celik, O.; Charles, E.;
Chaty, S.; Chaves, R. C. G.; Chekhtman, A.; Chen, A. W.; Chiang, J.;
Chiaro, G.; Ciprini, S.; Claus, R.; Cognard, I.; Cohen-Tanugi, J.;
Cominsky, L. R.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis,
A.; Decesar, M. E.; de Luca, A.; den Hartog, P. R.; de Palma, F.;
Dermer, C. D.; Desvignes, G.; Digel, S. W.; di Venere, L.; Drell,
P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Espinoza, C. M.;
Falletti, L.; Favuzzi, C.; Ferrara, E. C.; Focke, W. B.; Franckowiak,
A.; Freire, P. C. C.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.;
Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.;
Glanzman, T.; Godfrey, G.; Gotthelf, E. V.; Grenier, I. A.; Grondin,
M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.;
Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hessels, J.;
Hewitt, J.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Jackson,
M. S.; Janssen, G. H.; Jogler, T.; Johannesson, G.; Johnson, R. P.;
Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Johnston, S.; Kamae,
T.; Kataoka, J.; Keith, M.; Kerr, M.; Knodlseder, J.; Kramer, M.;
Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.;
Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Lyne, A. G.;
Manchester, R. N.; Marelli, M.; Massaro, F.; Mayer, M.; Mazziotta,
M. N.; McEnery, J. E.; McLaughlin, M. A.; Mehault, J.; Michelson,
P. F.; Mignani, R. P.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.;
Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori,
T.; Nemmen, R.; Nuss, E.; Ohno, M.; Ohsugi, T.; Orienti, M.; Orlando,
E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins,
J. S.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.;
Pletsch, H. J.; Porter, T. A.; Possenti, A.; Raino, S.; Rando, R.;
Ransom, S. M.; Ray, P. S.; Razzano, M.; Rea, N.; Reimer, A.; Reimer,
O.; Renault, N.; Reposeur, T.; Ritz, S.; Romani, R. W.; Roth, M.;
Rousseau, R.; Roy, J.; Ruan, J.; Sartori, A.; Saz Parkinson, P. M.;
Scargle, J. D.; Schulz, A.; Sgro, C.; Shannon, R.; Siskind, E. J.;
Smith, D. A.; Spandre, G.; Spinelli, P.; Stappers, B. W.; Strong,
A. W.; Suson, D. J.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.;
Theureau, G.; Thompson, D. J.; Thorsett, S. E.; Tibaldo, L.; Tibolla,
O.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.;
Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Venter, C.; Vianello,
G.; Vitale, V.; Wang, N.; Weltevrede, P.; Winer, B. L.; Wolff, M. T.;
Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.
Bibcode: 2013yCat..22080017A
Altcode:
Fermi was launched on 2008 June 11, carrying two gamma-ray instruments;
among them the Large Area Telescope (LAT). The LAT is sensitive to gamma
rays with energies from 20MeV to over 300GeV, with an on-axis effective
area of ~8000 cm2 above 1 GeV. The data used here to search for
gamma-ray pulsars span 2008 August 4 to 2011 August 4. Events were
selected with reconstructed energies from 0.1 to 100GeV and directions
within 2° of each pulsar position for pulsation searches (Section 3)
and 15° for spectral analyses (Section 6). (8 data files).
Title: The Second Fermi Large Area Telescope Catalog of Gamma-Ray
Pulsars
Authors: Abdo, A. A.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet,
J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Belfiore, A.;
Bellazzini, R.; Bhattacharyya, B.; Bissaldi, E.; Bloom, E. D.;
Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida,
M.; Bruel, P.; Buehler, R.; Burgay, M.; Burnett, T. H.; Busetto, G.;
Buson, S.; Caliandro, G. A.; Cameron, R. A.; Camilo, F.; Caraveo,
P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.;
Chaty, S.; Chaves, R. C. G.; Chekhtman, A.; Chen, A. W.; Chiang, J.;
Chiaro, G.; Ciprini, S.; Claus, R.; Cognard, I.; Cohen-Tanugi, J.;
Cominsky, L. R.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis,
A.; DeCesar, M. E.; De Luca, A.; den Hartog, P. R.; de Palma, F.;
Dermer, C. D.; Desvignes, G.; Digel, S. W.; Di Venere, L.; Drell,
P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Espinoza, C. M.;
Falletti, L.; Favuzzi, C.; Ferrara, E. C.; Focke, W. B.; Franckowiak,
A.; Freire, P. C. C.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.;
Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.;
Glanzman, T.; Godfrey, G.; Gotthelf, E. V.; Grenier, I. A.; Grondin,
M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.;
Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hessels, J.;
Hewitt, J.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Jackson,
M. S.; Janssen, G. H.; Jogler, T.; Jóhannesson, G.; Johnson, R. P.;
Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Johnston, S.; Kamae,
T.; Kataoka, J.; Keith, M.; Kerr, M.; Knödlseder, J.; Kramer, M.;
Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.;
Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Lyne, A. G.;
Manchester, R. N.; Marelli, M.; Massaro, F.; Mayer, M.; Mazziotta,
M. N.; McEnery, J. E.; McLaughlin, M. A.; Mehault, J.; Michelson,
P. F.; Mignani, R. P.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.;
Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori,
T.; Nemmen, R.; Nuss, E.; Ohno, M.; Ohsugi, T.; Orienti, M.; Orlando,
E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins,
J. S.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.;
Pletsch, H. J.; Porter, T. A.; Possenti, A.; Rainò, S.; Rando, R.;
Ransom, S. M.; Ray, P. S.; Razzano, M.; Rea, N.; Reimer, A.; Reimer,
O.; Renault, N.; Reposeur, T.; Ritz, S.; Romani, R. W.; Roth, M.;
Rousseau, R.; Roy, J.; Ruan, J.; Sartori, A.; Saz Parkinson, P. M.;
Scargle, J. D.; Schulz, A.; Sgrò, C.; Shannon, R.; Siskind, E. J.;
Smith, D. A.; Spandre, G.; Spinelli, P.; Stappers, B. W.; Strong,
A. W.; Suson, D. J.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.;
Theureau, G.; Thompson, D. J.; Thorsett, S. E.; Tibaldo, L.; Tibolla,
O.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.;
Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Venter, C.; Vianello,
G.; Vitale, V.; Wang, N.; Weltevrede, P.; Winer, B. L.; Wolff, M. T.;
Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.
Bibcode: 2013ApJS..208...17A
Altcode: 2013arXiv1305.4385T
This catalog summarizes 117 high-confidence >=0.1 GeV gamma-ray
pulsar detections using three years of data acquired by the Large
Area Telescope (LAT) on the Fermi satellite. Half are neutron stars
discovered using LAT data through periodicity searches in gamma-ray and
radio data around LAT unassociated source positions. The 117 pulsars
are evenly divided into three groups: millisecond pulsars, young
radio-loud pulsars, and young radio-quiet pulsars. We characterize the
pulse profiles and energy spectra and derive luminosities when distance
information exists. Spectral analysis of the off-peak phase intervals
indicates probable pulsar wind nebula emission for four pulsars, and
off-peak magnetospheric emission for several young and millisecond
pulsars. We compare the gamma-ray properties with those in the radio,
optical, and X-ray bands. We provide flux limits for pulsars with no
observed gamma-ray emission, highlighting a small number of gamma-faint,
radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains
emission models. Fermi's selection biases complement those of radio
surveys, enhancing comparisons with predicted population distributions.
Title: GMRT Discovery of PSR J1544+4937: An Eclipsing Black-widow
Pulsar Identified with a Fermi-LAT Source
Authors: Bhattacharyya, B.; Roy, J.; Ray, P. S.; Gupta, Y.;
Bhattacharya, D.; Romani, R. W.; Ransom, S. M.; Ferrara, E. C.; Wolff,
M. T.; Camilo, F.; Cognard, I.; Harding, A. K.; den Hartog, P. R.;
Johnston, S.; Keith, M.; Kerr, M.; Michelson, P. F.; Saz Parkinson,
P. M.; Wood, D. L.; Wood, K. S.
Bibcode: 2013ApJ...773L..12B
Altcode: 2013arXiv1304.7101B
Using the Giant Metrewave Radio Telescope, we performed deep
observations to search for radio pulsations in the directions of
unidentified Fermi-Large Area Telescope γ-ray sources. We report
the discovery of an eclipsing black-widow millisecond pulsar, PSR
J1544+4937, identified with the uncataloged γ-ray source FERMI
J1544.2+4941. This 2.16 ms pulsar is in a 2.9 hr compact circular
orbit with a very low mass companion (Mc > 0.017M
⊙). At 322 MHz this pulsar is found to be eclipsing for 13%
of its orbit, whereas at 607 MHz the pulsar is detected throughout the
low-frequency eclipse phase. Variations in the eclipse ingress phase are
observed, indicating a clumpy and variable eclipsing medium. Moreover,
additional short-duration absorption events are observed around the
eclipse boundaries. Using the radio timing ephemeris we were able to
detect γ-ray pulsations from this pulsar, confirming it as the source
powering the γ-ray emission.
Title: Detection of Fast Transients with Radio Interferometric Arrays
Authors: Bhat, N. D. R.; Chengalur, J. N.; Cox, P. J.; Gupta, Y.;
Prasad, J.; Roy, J.; Bailes, M.; Burke-Spolaor, S.; Kudale, S. S.;
van Straten, W.
Bibcode: 2013ApJS..206....2B
Altcode: 2013arXiv1302.3418B
Next-generation radio arrays, including the Square Kilometre Array
(SKA) and its pathfinders, will open up new avenues for exciting
transient science at radio wavelengths. Their innovative designs,
comprising a large number of small elements, pose several challenges
in digital processing and optimal observing strategies. The Giant
Metre-wave Radio Telescope (GMRT) presents an excellent test-bed for
developing and validating suitable observing modes and strategies for
transient experiments with future arrays. Here we describe the first
phase of the ongoing development of a transient detection system for
GMRT that is planned to eventually function in a commensal mode with
other observing programs. It capitalizes on the GMRT's interferometric
and sub-array capabilities, and the versatility of a new software
backend. We outline considerations in the plan and design of transient
exploration programs with interferometric arrays, and describe a pilot
survey that was undertaken to aid in the development of algorithms
and associated analysis software. This survey was conducted at 325 and
610 MHz, and covered 360 deg2 of the sky with short dwell
times. It provides large volumes of real data that can be used to test
the efficacies of various algorithms and observing strategies applicable
for transient detection. We present examples that illustrate the
methodologies of detecting short-duration transients, including the use
of sub-arrays for higher resilience to spurious events of terrestrial
origin, localization of candidate events via imaging, and the use
of a phased array for improved signal detection and confirmation. In
addition to demonstrating applications of interferometric arrays for
fast transient exploration, our efforts mark important steps in the
roadmap toward SKA-era science.
Title: Radio Detection of the Fermi-LAT Blind Search Millisecond
Pulsar J1311-3430
Authors: Ray, P. S.; Ransom, S. M.; Cheung, C. C.; Giroletti, M.;
Cognard, I.; Camilo, F.; Bhattacharyya, B.; Roy, J.; Romani, R. W.;
Ferrara, E. C.; Guillemot, L.; Johnston, S.; Keith, M.; Kerr, M.;
Kramer, M.; Pletsch, H. J.; Saz Parkinson, P. M.; Wood, K. S.
Bibcode: 2013ApJ...763L..13R
Altcode: 2012arXiv1210.6676R
We report the detection of radio emission from PSR J1311-3430, the
first millisecond pulsar (MSP) discovered in a blind search of Fermi
Large Area Telescope (LAT) gamma-ray data. We detected radio pulsations
at 2 GHz, visible for <10% of ~4.5 hr of observations using the
Green Bank Telescope (GBT). Observations at 5 GHz with the GBT and
at several lower frequencies with Parkes, Nançay, and the Giant
Metrewave Radio Telescope resulted in non-detections. We also report
the faint detection of a steep spectrum continuum radio source (0.1
mJy at 5 GHz) in interferometric imaging observations with the Jansky
Very Large Array. These detections demonstrate that PSR J1311-3430 is
not radio quiet and provide additional evidence that radio-quiet MSPs
are rare. The radio dispersion measure of 37.8 pc cm-3
provides a distance estimate of 1.4 kpc for the system, yielding a
gamma-ray efficiency of 30%, typical of LAT-detected MSPs. We see
apparent excess delay in the radio pulses as the pulsar appears from
eclipse and we speculate on possible mechanisms for the non-detections
of the pulse at other orbital phases and observing frequencies.
Title: Spectral energy distributions and age estimates of 40 massive
young stellar objects
Authors: Tanti, K. K.; Roy, J.; Duorah, K.
Bibcode: 2012AASP....2..139T
Altcode:
In this paper, we present the spectral energy distributions (SEDs)
of 40 massive young stellar objects (YSOs), detected from the NIR
imaging survey carried out by Varricatt et al. 2010 and estimated
their ages and masses. The SEDs of YSOs in 40 massive star forming
regions have been reconstructed using 2MASS, MSX, IRAS, IRAC &
MIPS, SCUBA, WISE, SPIRE and IRAM data, partly available from previous
works, using the on-line SED Fitting tool (SED Fitter) developed
by Robitaille et al. 2006, 2007. Apart from IRAS catalogue fluxes,
the fluxes in the Mid-IR and sub-mm/mm were derived directly from
the images. With the help of the analysis of SEDs, we have extracted
important physical and structural parameters for each of the massive
young stellar objects, along with the associated circumstellar disk and
envelope. The cumulative distribution of the stellar ages and masses
of the massive YSOs lead to a scenario for the formation history of
massive stars in their respective star forming regions.
Title: Radio Searches of Fermi LAT Sources and Blind Search Pulsars:
The Fermi Pulsar Search Consortium
Authors: Ray, P. S.; Abdo, A. A.; Parent, D.; Bhattacharya, D.;
Bhattacharyya, B.; Camilo, F.; Cognard, I.; Theureau, G.; Ferrara,
E. C.; Harding, A. K.; Thompson, D. J.; Freire, P. C. C.; Guillemot,
L.; Gupta, Y.; Roy, J.; Hessels, J. W. T.; Johnston, S.; Keith, M.;
Shannon, R.; Kerr, M.; Michelson, P. F.; Romani, R. W.; Kramer, M.;
McLaughlin, M. A.; Ransom, S. M.; Roberts, M. S. E.; Saz Parkinson,
P. M.; Ziegler, M.; Smith, D. A.; Stappers, B. W.; Weltevrede, P.;
Wood, K. S.
Bibcode: 2012arXiv1205.3089R
Altcode:
We present a summary of the Fermi Pulsar Search Consortium (PSC), an
international collaboration of radio astronomers and members of the
Large Area Telescope (LAT) collaboration, whose goal is to organize
radio follow-up observations of Fermi pulsars and pulsar candidates
among the LAT gamma-ray source population. The PSC includes pulsar
observers with expertise using the world's largest radio telescopes that
together cover the full sky. We have performed very deep observations of
all 35 pulsars discovered in blind frequency searches of the LAT data,
resulting in the discovery of radio pulsations from four of them. We
have also searched over 300 LAT gamma-ray sources that do not have
strong associations with known gamma-ray emitting source classes and
have pulsar-like spectra and variability characteristics. These searches
have led to the discovery of a total of 43 new radio millisecond pulsars
(MSPs) and four normal pulsars. These discoveries greatly increase
the known population of MSPs in the Galactic disk, more than double
the known population of so-called `black widow' pulsars, and contain
many promising candidates for inclusion in pulsar timing arrays.
Title: Tracking the dispersion measure variation of millisecond
pulsars using simultaneous dual frequency timing
Authors: Kumar, Ujjwal; Gupta, Y.; Roy, J.; Bhat, R.; van Straten,
W.; Bailes, M.
Bibcode: 2011ASInC...3..118K
Altcode:
Dispersion Measure (DM) is one of the most important factors which
can limit the accuracy with which one is able to time pulsars. The
DM of a pulsar, in general, changes significantly with time due to
reasons such as proper motion of the pulsar, plasma density changes in
the binary orbit, drift of intervening inhomogeneous ISM, solar wind
plasma. Hence, it becomes necessary to keep track of the changing DM,
especially for pulsar timing applications requiring very high timing
precision, such as the various pulsar timing array projects which aim
to detect gravitational waves. Drawing motivation from this as well
as from an earlier work by Ahuja et al. (2005), who had achieved a
DM accuracy of 1 part in 10^4 for long period pulsars, we initiated
a project aimed to do regular simultaneous multi-frequency timing
observation of a selected set of millisecond pulsars using the GMRT
with the aim of studying (i) accurate DM variations of MSPs and their
effects on timing accuracy and (ii) DM variations due to the solar
corona and the solar wind. Preliminary results from the observations
from previous three cycles are already demonstrating accuracies of DM
measurements of a few parts in 10^5 for the MSP observations. With the
further enhancements in observing modes of the GMRT software back-end
that are planned, coupled with improved analysis techniques, it will
soon be possible to get to our target of 1 part in 10^5 or better.
Title: A Question and Answer Guide to Astronomy
Authors: Bely, Pierre-Yves; Christian, Carol; Roy, Jean-René
Bibcode: 2010qaga.book.....B
Altcode:
Stars; The Solar System; The Earth; The Moon; Celestial phenomena;
The Universe; Life in the Universe; History of astronomy; Telescopes;
Amateur astronomy; Bibliography; References; Index.
Title: Glitches from the Young Pulsar J1833-1034
Authors: Roy, J.; Gupta, Y.; Lewandowski, W.
Bibcode: 2009ASPC..407..299R
Altcode:
We present preliminary results from out timing study of the young
pulsar, PSR J1833-1034, in the supernova remnant G21.5-0.9. From the
detailed behaviour of the timing residuals, we are able to infer the
occurrence of as many as three glitches over a span of 3.5 years. The
fractional change of the rotational frequency during these glitches is
found to be in the range 1× 10-9 to 3×10-9. The
final model fitted to the timing data yields accurate estimates for
the period, its first and second derivatives, and hence a plausible
value of the braking index.
Title: HR 8799 and the Search of Jupiter-like Planets Around Young
& Nearby Early-Type Stars.
Authors: Marois, Christian; Macintosh, Bruce; Roy, Jean-Rene; Patience,
Jennifer; Barman, Travis; Zuckerman, Ben; Song, Insoek; Lafreniere,
David; Doyon, Rene
Bibcode: 2009noao.prop..306M
Altcode:
Following our HR 8799 3-planet system discovery at Gemini, we
propose to search for an additional planet at 10 AU in this system
and to pursue our ongoing volume-limited (<55 pc) deep AO/ADI A-
& F-type star IDPS survey. Analyzes of star forming regions have
shown that A-type stars have more frequent/massive disks than less
massive stars, potentially triggering more massive planet formation
on wider orbits. Stars as massive as A-type stars have been neglected
in AO searches, including the Gemini Deep Planet Survey, while radial
velocity surveys have reduced sensitivity for such stars. Thus planet/BD
formation around more massive stars remains unconstrained. After
combining this A-type star survey with our previous GDPS survey and
new FGKM proposed targets for NICI, we will have, for the first time, a
broader picture of the population of massive planets at large semi-major
axes around a wide range of stellar mass.
Title: Catching a Runaway in the Galactic Center: A Study of the
IRS8 Bowshock
Authors: Fisher, R. S.; Volk, K.; Roy, J. -R.; Geballe, T. R.
Bibcode: 2007RMxAC..29..153F
Altcode:
In this summary we present early results from our on-going study of
the Galactic Center source IRS8.
Title: The K-Band Spectrum of the Hot Star in IRS 8: An Outsider in
the Galactic Center?
Authors: Geballe, T. R.; Najarro, F.; Rigaut, F.; Roy, J. -R.
Bibcode: 2006ApJ...652..370G
Altcode: 2006astro.ph..7550G
Using adaptive optics at the Gemini North telescope, we have obtained a
K-band spectrum of the star near the center of the luminous Galactic
center bow shock IRS 8, as well as a spectrum of the bow shock
itself. The stellar spectrum contains emission and absorption lines
characteristic of an O5-O6 giant or supergiant. The wind from such a
star is fully capable of producing the observed bow shock. However,
both the early spectral type and the apparently young age of the star,
if it is single, mark it as unique among hot stars within 1 pc of
the center. Based on data obtained at the Gemini Observatory,
which is operated by the Association of Universities for Research in
Astronomy, Inc., under a cooperative agreement with the NSF on behalf
of the Gemini partnership: the National Science Foundation (US), the
Particle Physics and Astronomy Research Council (UK), the National
Research Council (Canada), CONICYT (Chile), the Australian Research
Council (Australia), CNPq (Brazil), and CONICET (Argentina).
Title: HI signal from the epoch of reionization: A pilot observation
with the GMRT
Authors: Roshi, D. A.; Sethi, S. K.; Pen, U. -L.; Peterson, J.;
Subrahmanyan, R.; Chang, T. -C.; Hirata, C.; Roy, J.; Gupta, Y.
Bibcode: 2006IAUJD..12E..50R
Altcode:
A key problem in modern cosmology is understanding the epoch of
reionization. We have initiated a programme for spectral-line imaging
of redshifted 21-cm HI line from neutral hydrogen at the reionization
epoch: our observations use the 150-MHz band of the Giant Meter Wave
Radio Telescope (GMRT). The observing frequency corresponds to a
redshift of about 8.5. Analysis of data taken to date is in progress
and we present a status report.
Title: The Evolving Sociology of Ground-Based Optical and Infrared
Astronomy at the Start of the 21ST Century
Authors: Roy, Jean-Rene; Mountain, Matt
Bibcode: 2006ASSL..335...11R
Altcode: 2006osa6.book...11R
By looking back at the last half century and beyond, an understanding
emerges in the patterns and influences of the social, fiscal
and institutional development of astronomical institutions and
observatories. In this paper, the authors review many changes that have
transformed how astronomers build and use their "great telescopes";
they also examine the evolving process that maximizes the productivity
and impact of undertaking modern ground-based optical/infrared
astronomy. The integration of modern engineering and experimental
practices, broadened access to largescale funding and international
competition, all have a role in these changes. A changing social
paradigm has moved these ventures from the scientific elite into
the realm and structure of tightly managed projects involving
close partnerships between engineers and scientists. Astronomer's
observational methods have changed in fundamental ways as well, driven
by the complexity of the instruments used and their tremendous cost. The
conclusion of this paper is that optical/infrared ground-based astronomy
is in transition. "Hundred-million-dollar-scale" 8m to 10m telescopes
have been erected and now our communities have billion-dollar-scale
ambitions. To realize these ambitions, the same communities need to
relinquish cherished notions of individual and even institutional
dominance and merge into large, productive consortia consisting of
institutions and multi-national agencies.
Title: Great Observatories Origins Deep Survey (GOODS)
Authors: Dickinson, Mark; Bergeron, Jacqueline; Casertano, Stefano;
Cesarsky, Catherine; Chary, Ranga-Ram; Cristiani, Stefano; Eisenhardt,
Peter; Elbaz, David; Fall, Michael; Ferguson, Henry; Fosbury, Robert;
Giacconi, Riccardo; Giavalisco, Mauro; Grogin, Norman; Hanisch, Robert;
Hauser, Michael; Hook, Richard; Jorgensen, Inger; Koekemoer, Anton;
Ledlow, Michael; Livio, Mario; Mobasher, Bahram; Padovani, Paolo;
Papovich, Casey; Reach, William; Renzini, Alvio; Rieke, Marcia;
Rosati, Piero; Roth, Katherine; Roy, Jean-Rene; Schreier, Ethan;
Stern, Daniel; Stiavelli, Massimo; Takamiya, Marianne; Tollestrup,
Eric; Urry, Megan; Williams, Robert; Winge, Claudia; Wright, Edward
Bibcode: 2004sptz.prop..169D
Altcode:
We propose a SIRTF Legacy Project, the Great Observatories Origins
Deep Survey, to study galaxy formation and evolution over a wide range
of redshift and cosmic lookback time. The survey will determine the
galaxies' mass assembly history, stellar populations, and energetic
output from star formation (SF) and AGN. By observing at lambda >3um,
SIRTF measures the rest-frame near- and mid-IR light from objects at
1<z<6, but very deep observations are needed, to detect "ordinary"
objects at these high redshifts. We propose to survey approximately 300
arcmin^2 at 3.6-8um with IRAC and at 24um with MIPS, reaching far deeper
flux limits than observations planned by the GTO programs. The survey
builds on the deepest observations of NASA's other Great Observatories,
HST and Chandra, and on a partnership with astronomers at Gemini and
ESO, with a commitment of extensive VLT support. The IRAC observations
will be capable of detecting rest-frame near-IR light from progenitors
of galaxies like the Milky Way out to z=4, and will enable us to study
the galaxy stellar mass distribution versus cosmic history. The MIPS
observations will provide the best opportunity to detect emission from
dust-obscured SF in ordinary,Lyman break galaxies out to z=2.5, and,
in concert with the Chandra data, will enable a census of supermassive
central black holes in obscured and unobscured AGN. An Ultradeep IRAC
field will probe the faintest sources and provide the best lower limits
to the extragalactic background light at 3.6-8um. By combining space-
and ground-based observations, we will create a public data archive
extending from X-ray through centimeter radio wavelengths, with a large
sample of objects out to the highest known redshifts. This survey will
give a uniquely comprehensive history of galaxies, from early epochs
to the relatively recent past, and will serve as a bridge to future
exploration in these wavelength and redshift regimes with NGST. Data from this program was split into multiple program IDs. You can
find the data in program IDs 169, 194
Title: A Bow Shock of Heated Dust Surrounding Galactic Center Source
IRS 8
Authors: Geballe, T. R.; Rigaut, F.; Roy, J. -R.; Draine, B. T.
Bibcode: 2004ApJ...602..770G
Altcode:
High-resolution images in the H and K bands obtained by the Gemini
North Telescope of the peculiar Galactic center source, IRS 8, reveal
a central pointlike object enveloped in a remarkable bow shock, whose
apex is located 0.2" to the northeast. The H-K' color of the bow shock
is considerably redder than that of the central star. A United Kingdom
Infrared Telescope (UKIRT) K-band spectrum reveals that the combined
spectrum of the point source and bow shock is nearly featureless and
that no shocked line emission (e.g., from H2) is physically
associated with the bow. We interpret the bow as resulting from the
interaction of the envelope or wind of the central star of IRS 8 with
the extension of the northern arm of Sgr A West and/or the circumnuclear
disk, and its emission as coming from radiatively heated, and possibly
shock heated, dust.
Title: A Bow Shock of Heated Dust Surrounding IRS 8
Authors: Rigaut, F.; Geballe, T. R.; Roy, J. -R.; Draine, B. T.
Bibcode: 2003ANS...324..551R
Altcode: 2003ANS...324a.551R
No abstract at ADS
Title: A Bow Shock of Heated Dust Surrounding the Galactic Center
Source IRS 8
Authors: Geballe, T. R.; Rigaut, F.; Roy, J. -R.; Draine, B. T.
Bibcode: 2002AAS...20114503G
Altcode: 2003BAAS...35..571G
High resolution H and K images obtained by the Gemini North Telescope
of the peculiar infrared source, IRS 8, located roughly 30" north of
the Galactic center, reveal a central pointlike object enveloped in a
remarkable bow-shock, whose apex is located 0.2'' to the northeast. The
H-K' color of the bow shock is considerably redder than that of the
central star. A UKIRT K band spectrum reveals that the central object
of IRS 8 has a featureless continuum and that no shocked line emission
(e.g., from H2) is physically associated with the bow. We
interpret the bow as resulting from the interaction of the envelope or
wind of the central star of IRS 8 with an extension of the northern arm
of Sgr A West or with the circumnuclear molecular ring, and its emission
as coming from a combination of shock- and radiatively heated dust. IRS
8 may have been flung out from the central cluster of hot stars.
Title: Water Experiments Related To The "Von Karman Sodium" Dynamo
Project
Authors: Marie, L.; Bourgoin, M.; Petrelis, F.; Roy, J.; Burguete,
J.; Chiffaudel, A.; Daviaud, F.; Fauve, S.; Odier, P.; Pinton, J. -F.
Bibcode: 2002AIPC..622..453M
Altcode: 2002exch.conf..453M
The purpose of the "Von Karman Sodium" (V.K.S.) experiment is
to study the "Dynamo Effect," namely the spontaneous generation
of magnetic field in a flow of electrically conducting fluid. The
device has been built at CEA / Cadarache, in collaboration with CEA /
Saclay, Ecole Normale Superieure de Lyon and Ecole Normale Superieure
de Paris. It consists of a cylindrical vessel, filled with liquid
Sodium, in which two coaxial rotating disks induce a Von-Karman type
flow. Several experimental runs have taken place since June 2000. In
order to optimize the V.K.S. set-up, a half-scale water prototype has
also been built. It has allowed us to measure mean velocity profiles,
as well as pressure fluctuations and mechanical power dissipation. We
have observed that under certain circumstances the mean component of
the turbulent flow can undergo a global bifurcation.
Title: The Hazards of Imaging Spectrophotometry with Interference
Filters
Authors: Dutil, Yvan; Roy, Jean-René
Bibcode: 2001AJ....122.1644D
Altcode:
Narrowband-filter imaging spectrophotometry is a powerful tool
for studying the spatial behavior of physical parameters, such
as interstellar reddening, excitation, electron temperature, and
densities or chemical abundances across extended objects such as
nebulae and galaxies. We explore the hazards and technical limits of
the method of spectral imaging with narrowband interference filters. We
discuss the specific application of statistical errors involved in the
estimation of abundance gradients from nebular line flux measurements
and the impact of those errors on interpretation. We demonstrate that
a sample of at least 16 H II regions is needed for a meaningful and
robust description of radial abundance gradients in disk galaxies. We
also discuss the systematic errors introduced by the uncertainty
related to the subtraction of the underlying stellar continuum from
monochromatic emission-line images; we demonstrate that the quality
of subtraction of the underlying continuum is the main limit on the
precision of imaging spectrophotometry with narrowband filters. Finally,
we investigate the impact of selection effects on the derivation of
physical parameters from measurements involving the ratio of two or more
spectral lines. Parts of this work were performed at the Université
Laval and at the Defence Research Establishment Valcartier.
Title: The Start of Scientific Observations with the Gemini North
Telescope
Authors: Roy, J. -R.
Bibcode: 2001AAS...198.1901R
Altcode: 2001BAAS...33..813R
The Gemini North Telescope was used to obtain science data during the
second half of 2000 and during the first semester of 2001. Two visitor
instruments were used: HOKUPA'A/Quirc, the Adaptive Optics System
built and operated by the Adaptive Optics Group of the University of
Hawaii, and OSCIR, the mid-infrared camera built and operated by the
University of Florida. Highlights of some of the results obtained by
these instruments will be presented. For example, it will be shown that
near-infrared photometry from adaptive optics images, using the Gemini
North Telescope, is a powerful tool to explore the different stellar
populations of the Galactic Center. Depending on the progress with
commissioning the Near Infrared Imager (NIRI), some early results from
this first facility instrument will be presented. A brief description
of the instruments that will become available on both Gemini North
and South during the coming year will be given.
Title: The Trajectory of the Jet in NGC 4258
Authors: Daigle, Anik; Roy, Jean-René
Bibcode: 2001ApJ...552..144D
Altcode:
The large spiral galaxy NGC 4258 (M106) harbors the nearest
extragalactic astrophysical jet. While low-resolution radio and X-ray
observations indicate that the jet propagates outside the galaxy disk,
high-resolution optical and CO millimeter observations point instead
to a propagation within the gaseous disk of the galaxy. We have
used a simple analytical model to explore a scenario where the jet
propagates at an angle of ~2deg with respect to the plane
of the galaxy in the inner disk and is forced out of the galaxy plane
at a radius of ~5 kpc. This scenario brings together the in-the-disk
and out-of-the-disk views into a hybrid model which accounts for
most of the observed properties of the jet. We show that (1) the
component normal to the disk plane of the forces acting on the jet,
dominated by ram pressure, has an amplitude sufficient to propel the
jet out of the main disk at galactocentric distances of about 4-5 kpc;
(2) the apparent deflections of the jet are probably caused by forces
acting within the plane of the disk for the first few kiloparsecs, by
the projection effect of the curved trajectory exiting the disk, and
by chimney-type structures popping out of the disk at r>4 kpc. We
suggest that the rich outer filamentary structures of the jet are due
to breakout into the low-pressure halo gas.
Title: Evidence for a Morphological Evolution of Spiral Galaxies
Authors: Dutil, Yvan; Roy, Jean-René
Bibcode: 2001IAUS..204..387D
Altcode:
A detail analysis of the oxygen abundance profile has been carried on a
sample of spiral galaxies from which very good data was available. The
early-type galaxies of our sample display gradients that are flatter
and overall levels of O/H abundances that are higher than those of
normal late-type galaxies. Early-type galaxies show an identical trend
in the behavior of extrapolated central abundance versus morphological
type to that shown by late-type galaxies with strong bars, even in the
absence of a bar. On a diagram showing extrapolated central abundances
versus morphological types, two clearly separated sequences appear:
late-type barred galaxies and early-type (barred or unbarred) galaxies
clearly fall on a sequence 0.5 dex in abundance below that of normal
late-type galaxies. This behavior is consistent with theoretical
model of morphological evolution of disk galaxies by the formation
and dissolution of a bar over a period of a few 109 yr,
where later type galaxies (Sd, Sc, Sbc) evolve into earlier-type disk
galaxies (Sb, Sa) through transitory SBc and SBb phases.
Title: The science case for the multi-conjugate adaptive optics
system on the Gemini South Telescope
Authors: Rigaut, Francois; Roy, Jean-Rene
Bibcode: 2001scma.book.....R
Altcode:
No abstract at ADS
Title: Physical Parameters of Erupting Luminous Blue Variables:
NGC 2363-V1 Caught in the Act
Authors: Drissen, Laurent; Crowther, Paul A.; Smith, Linda J.; Robert,
Carmelle; Roy, Jean-René; Hillier, D. John
Bibcode: 2001ApJ...546..484D
Altcode: 2000astro.ph..8221D
A quantitative study of the luminous blue variable NGC 2363-V1
in the Magellanic galaxy NGC 2366 (D=3.44 Mpc) is presented,
based on ultraviolet and optical Hubble Space Telescope STIS
spectroscopy. Contemporary WFPC2 and William Herschel Telescope
imaging reveals a modest V-band brightness increase of ~0.2 mag
per year between 1996 January-1997 November, reaching V=17.4 mag,
corresponding to MV=-10.4 mag. Subsequently, V1 underwent a
similar decrease in V-band brightness, together with a UV brightening
of 0.35 mag from 1997 November to 1999 November. The optical spectrum
of V1 is dominated by H emission lines, with Fe II, He I and Na I also
detected. In the ultraviolet, a forest of Fe absorption features and
numerous absorption lines typical of mid-B supergiants (such as Si II,
Si III, Si IV, C III, C IV) are observed. From a spectral analysis
with the non-LTE, line-blanketed code of Hillier & Miller, we
derive stellar parameters of T*=11 kK, R*=420
Rsolar, log (L/Lsolar)=6.35 during 1997 November,
and T*=13 kK, R*=315 Rsolar, log
(L/Lsolar)=6.4 for 1999 July. The wind properties of V1
are also exceptional, with M~=4.4×10-4Msolar
yr-1 and v∞~=300 km s-1, allowing for
a clumped wind (filling factor=0.3) and assuming H/He~4 by number. The
presence of Fe lines in the UV and optical spectrum of V1 permits an
estimate of the heavy elemental abundance of NGC 2363 from our spectral
synthesis. Although some deficiencies remain, allowance for charge
exchange reactions in our calculations supports a SMC-like metallicity,
that has previously been determined for NGC 2363 from nebular oxygen
diagnostics. Considering a variety of possible progenitor stars,
V1 has definitely undergone a giant eruption, with a substantial
increase in stellar luminosity, radius, and almost certainly mass-loss
rate, such that its stellar radius increased at an average rate of
~4 km s-1 during 1992 October-1995 February. The stellar
properties of V1 are compared to other LBVs, including η Car and HD
5980 during its brief eruption in 1994 September, the latter newly
analyzed here. The mass-loss rate of the HD 5980 eruptor compares
closely with V1, but its bolometric luminosity was a factor ~6 times
larger. Based on observations with the NASA/ESA Hubble Space Telescope,
obtained at the Space Telescope Science Institute, which is operated
by AURA, Inc., under NASA contract NAS 5-26555.
Title: Time Scale of Chemical Enrichment, Transport, and Mixing
Authors: Roy, Jean-René
Bibcode: 2001ASPC..245..438R
Altcode: 2001aats.conf..438R
No abstract at ADS
Title: The H II Regions of the Extreme Outer Disk of NGC 628
Authors: Lelièvre, Mario; Roy, Jean-René
Bibcode: 2000AJ....120.1306L
Altcode:
Employing deep Hα narrowband imagery, we identified and measured
the fluxes of 137 small H II regions in the extreme outer disk
(R>=R25) of the nearly face-on, Sc I galaxy NGC
628. A majority of these H II regions are located in two faint,
outer spiral arms visible in H I maps. The faintest H II regions that
could be measured have fluxes of only a few times 10-16
ergs cm-2 s-1, which correspond to luminosities
of ~1036 ergs s-1, or a fraction of the Orion
Nebula luminosity. The most distant object detected is at R~27 kpc
from the galaxy center. The massive star formation rate, as measured
from the azimuthally averaged Hα flux, is consistent with a monotonic
decrease as far as R~1.3R25 (20 kpc), where there is a
sharp drop. The Schmidt law for the whole disk of NGC 628 corresponds
to a relatively steep power law with n=2.9+/-0.2, but it ``fails''
below Σgas<=4 Msolar pc-2; the
index depends strongly on the CO data used. We derived the luminosity
function (LF) of 598 H II regions over the whole disk, and we compared
the shapes of the cumulative LFs between R>=R25 and
R<R25 the LF of the outer regions is significantly
steeper than that of the inner regions.
Title: The O/H Distribution in NGC 7479: Evidence for a Minor
Merger Event
Authors: Martin, Pierre; Lelièvre, Mario; Roy, Jean-René
Bibcode: 2000ApJ...538..141M
Altcode:
Results of emission-line spectrophotometry of 68 H II regions in the
strongly barred spiral galaxy NGC 7479 obtained with the Multi-Object
Spectrograph at the Canada-France-Hawaii Telescope are presented. The
average nebular extinction across the galaxy disk is Av~1.1
mag. There is a radial trend (-0.042+/-0.010 mag kpc-1)
in the values of reddening suggesting a global difference of about
1.1 mag between the inner and outer parts of the galaxy. All the H II
regions fall within the well-defined sequences of normal H II regions
in the standard diagnostic diagrams [O III]/Hβ versus [N II]/Hα, and
[O III]/Hβ versus [O I]/Hα. The values of excitation ([O III]/Hβ)
of the regions located in the western arm are higher by about 0.4 dex
compared to those of the eastern arm and central regions. There is
evidence that the ionization parameter is higher and the electronic
density lower in these regions. The global O/H abundance gradient is
shallow (~-0.025+/-0.005 dex kpc-1), in agreement with what
is found for galaxies with a strong bar. No break is seen in the O/H
radial gradient. The azimuthal O/H variations in the disk are small at
less than 0.3 dex. These results are discussed in the framework of a
merger in which NGC 7479 captured a small galaxy about 3×108
yr ago.
Title: A continuous low star formation rate in IZw 18?
Authors: Legrand, F.; Kunth, D.; Roy, J. -R.; Mas-Hesse, J. M.; Walsh,
J. R.
Bibcode: 2000A&A...355..891L
Altcode: 2000astro.ph..1302L
Deep long-slit spectroscopic observations of the blue compact galaxy IZw
18 obtained with the CFH 3.6 m Telescope are presented. The very low
value of oxygen abundance previously reported is confirmed and a very
homogeneous abundance distribution is found (no variation larger than
0.05 dex) over the whole ionized region. We concur with \cite{TT96}
and \cite{DRD97} that the observed abundance level cannot result
from the material ejected by the stars formed in the current burst,
and propose that the observed metals were formed in a previous star
formation episode. Metals ejected in the current burst of star formation
remain most probably hidden in a hot phase and are undetectable using
optical spectroscopy. We discuss different scenarios of star formation
in IZw 18. Combining various observational facts, for instance the
faint star formation rate observed in low surface brightness galaxies
(Van Zee et al. 1997c), it is proposed that a low and continuous rate
of star formation occurring during quiescent phases between bursts
could be a significant source of metal enrichment of the interstellar
medium. This research has made use of NASA's Astrophysics Data System
Abstract Service.
Title: The Star Formation History of the Starburst Region NGC 2363
and its Surroundings
Authors: Drissen, Laurent; Roy, Jean-René; Robert, Carmelle; Devost,
Daniel; Doyon, René
Bibcode: 2000AJ....119..688D
Altcode: 1999astro.ph.10476D
We present Hubble Space Telescope optical images and UV spectra, as well
as ground-based near-infrared images of the high surface-brightness
giant H II region NGC 2363 (NGC 2366-I) and its surroundings. The
massive star content of the southern end of the dwarf irregular
galaxy NGC 2366 is investigated, with an emphasis on Wolf-Rayet and
red supergiant stars, and we attempt the reconstruction of the time
sequence of the most recent episode of massive star formation at
the southwestern tip of the galaxy. The ages of the clusters are,
respectively, 10 Myr for NGC 2366-II, 2.5-5 Myr for NGC 2363-B,
and less than 1 Myr for NGC 2363-A. In particular, we show that the
most massive supercluster A of NGC 2363 is still embedded in dust;
from the photoevaporative erosion or ``cleaning'' timescale of the
associated cloud, we infer its age to be ~106 yr or less. We
conclude that the star-forming complex NGC 2366-I and 2366-II is a
good example of a multiple stage starburst with a characteristic age
decreasing from 10 Myr to less than 1 Myr over a linear scale of 400
pc. The age sequence of the stars and the gas kinematics suggest that
these powerful star formation episodes are being triggered by a small
passing-by satellite. Based on observations with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by AURA, Inc., under NASA contract NAS 5-26555.
Title: Star Formation in Subcritical Environments
Authors: Lelievre, M.; Roy, J. -R.; Martin, P.
Bibcode: 2000ASPC..221..129L
Altcode: 2000sgdg.conf..129L
No abstract at ADS
Title: Formation d'étoiles massives en régime sous-critique.
Authors: Lelièvre, M.; Roy, J. -R.; Martin, P.
Bibcode: 1999JRASC..93R.185L
Altcode:
No abstract at ADS
Title: La transformation des galaxies spirales
Authors: Dutil, Y.; Roy, J. -R.
Bibcode: 1999BCFHT..40...18D
Altcode:
No abstract at ADS
Title: Chemical Evidence for Morphological Evolution of Spiral
Galaxies
Authors: Dutil, Yvan; Roy, Jean-René
Bibcode: 1999ApJ...516...62D
Altcode:
Using the methods of spectrophotometric imagery and multislit
spectroscopy, we have derived the radial abundance profiles from
O/H measurements in 549 H II regions of eight early-type spiral
galaxies. We then compared the characteristic abundance levels and
radial distributions of this group of spirals with those of late-type
galaxies. The early-type galaxies of our sample display gradients
that are flatter and overall levels of O/H abundances that are higher
than those of normal late-type galaxies. Early-type galaxies show an
identical trend in the behavior of extrapolated central abundance versus
morphological type to that shown by late-type galaxies with strong bars,
even in the absence of a bar. On a diagram showing extrapolated central
abundances versus morphological types, two clearly separated sequences
appear: late-type barred galaxies and early-type (barred or unbarred)
galaxies clearly fall on a sequence ~0.5 dex in abundance below that
of normal late-type galaxies. This behavior is consistent with a
scenario of morphological evolution of disk galaxies by the formation
and dissolution of a bar over a period of a few 109 yr,
where later type galaxies (Sd, Sc, Sbc) evolve into earlier-type disk
galaxies (Sb, Sa) through transitory SBc and SBb phases.
Title: Modeling the Radial Abundance Distribution of the Transition
Galaxy NGC 1313
Authors: Mollá, Mercedes; Roy, Jean-René
Bibcode: 1999ApJ...514..781M
Altcode: 1999astro.ph..3129M
NGC 1313 is the most massive disk galaxy showing a flat radial abundance
distribution in its interstellar gas, a behavior generally observed in
Magellanic and irregular galaxies. We have attempted to reproduce this
flat abundance distribution using a multiphase chemical evolution model,
which has been previously used successfully to depict other spiral
galaxies along the Hubble morphological sequence. We found that it
is not possible to reproduce the flat radial abundance distribution
in NGC 1313 and at the same time be consistent with observed radial
distributions of other key parameters, such as the surface gas density
and star formation profiles. We conclude that a more complicated
galactic evolution model, including radial flows and possibly mass
loss due to supernova explosions and winds, is necessary to explain
the apparent chemical uniformity of the disk of NGC 1313.
Title: The Ionizing Star Clusters of Giant H II Regions in NGC 2403
Authors: Drissen, Laurent; Roy, Jean-René; Moffat, Anthony F. J.;
Shara, Michael M.
Bibcode: 1999AJ....117.1249D
Altcode:
We present the results of a study on the massive star population down
to about M_V~-3.1, or 12-15 M_solar, of the most luminous giant H II
regions in the nearby spiral galaxy NGC 2403, based on Hubble Space
Telescope images and ground-based spectrograms. Particular emphasis
is placed on the distribution of the Wolf-Rayet and red supergiant
stars and the information they provide about the recent star-forming
history of these large complexes. We find direct evidence for the
presence of Wolf-Rayet (WR) stars in five of the six giant H II regions
investigated; 25-40 WR stars are inferred for the sole NGC 2403-I giant
H II region. Red supergiant (RSG) stars are mainly distributed over a
more extended halo, while the young blue stars and most WR stars are in
or close to a compact core. One appears to be seeing young cores of O
and WR stars surrounded by older halos containing red supergiants. We
propose a scenario in which RSG stars belonging to an early phase of
star formation were followed by a more recent burst corresponding
to a very blue mean sequence. Delayed trigger with preheating over
several 100 pc by the first generation of massive stars allowed the
build-up of the required confinement for the production of parsec-scale
cluster cores with luminosity up to a few times 10^6 L_solar. Finally,
we present some interesting objects found in the field of NGC 2403
outside the giant H II regions, such as field WR stars, globular
clusters and background galaxies.
Title: The stellar content of NGC2363 and its surroundings
Authors: Drissen, L.; Roy, J. -R.; Robert, C.; Devost, D.
Bibcode: 1999IAUS..193..741D
Altcode:
No abstract at ADS
Title: Wolf-Rayet stars in IZw 18
Authors: Legrand, F.; Kunth, D.; Roy, J. -R.; Mas-Hesse, J. M.; Walsh,
J. R.
Bibcode: 1999IAUS..193..606L
Altcode:
No abstract at ADS
Title: Chemical Evolution of Low Mass Disc Galaxies
Authors: Mollá, Mercedes; Roy, Jean-René
Bibcode: 1999cezh.conf..154M
Altcode: 1999astro.ph..3144M
We show that the multiphase chemical evolution model reproduces
the correlations obtained along the spiral sequence, dwarf galaxies
included. However the apparent spatial chemical uniformity observed
in some irregular galaxies cannot be reproduced with it. An
evolutionary model has been developed and tested to explain flat
gradients. Preliminary results, obtained with a new code including
supernova winds and radial flows, suggest that radial flows are probably
responsible for this uniformity.
Title: HST/STIS Witnesses a Major LBV Eruption
Authors: Crowther, P. A.; Drissen, Laurent; Smith, L. J.; Roy,
Jean-Rene; Hillier, D. J.
Bibcode: 1999upse.conf....9C
Altcode:
No abstract at ADS
Title: KIR: first light.
Authors: Doyon, R.; St-Louis, N.; Robert, C.; Devost, D.; Roy, J. -R.;
Drissen, L.
Bibcode: 1998JRASC..92R.316D
Altcode:
No abstract at ADS
Title: Support capability requirements of 8-m-telescope science
Authors: Puxley, Phil J.; Boroson, Todd A.; Roche, Patrick; Roy,
Jean-Rene
Bibcode: 1998SPIE.3349..380P
Altcode:
Science workshops were held throughout the Gemini partnership during
the second half of 1997 with the aims of identifying and quantifying the
supporting capabilities required to enhance the utility and efficiency
of the Gemini 8m telescopes. These workshops, held separately in the
US, UK, Canada and South America, ensured representation programs
were considered in detail sufficient to understand the requirements
for their execution on Gemini as well as for any preparatory
observations. The desire for wide-field optical and near-IR imaging
was frequently identified with an average of one-half to one night
of these survey observations per night of Gemini follow-up. Two other
common themes were high angular resolution imaging and rapid response
to target-of-opportunity events.
Title: The determination of enantiomeric purity and absolute
configuration by vibrational circular dichroism spectroscopy
Authors: Nafie, Laurence A.; Long, Fujin; Freedman, Teresa B.; Buijs,
Henry; Rilling, Allan; Roy, Jean-Rene; Dukor, Rina K.
Bibcode: 1998AIPC..430..432N
Altcode: 1998fts..conf..432N
There is an increasing need for new methods to determine percent
enantiomeric excess (%ee) in chiral molecules. Four sets of
determinations of %ee using Fourier transform infrared vibrational
circular dichroism (FTIR-VCD) have been performed using three different
instruments and several kinds of samples. These include measurements
for neat α-pinene with two different FTIR spectrometers equipped
with a mercury cadmium telluride (MCT) detector, measurements for
lysine in H2O using one of the MCT instruments, and measurements for
3-methylcyclohexanone in CCl4 solution. We find that FT-VCD spectroscopy
is capable of measuring %ee in the range of 1% or better for these
samples using one to several hours of spectral collection time.
Title: Bars and the chemistry of disk galaxies.
Authors: Roy, J. -R.; Walsh, J. R.
Bibcode: 1998JRASC..92...26R
Altcode:
No abstract at ADS
Title: Detection of WR stars in the metal-poor starburst galaxy
IZw 18.
Authors: Legrand, F.; Kunth, D.; Roy, J. -R.; Mas-Hesse, J. M.; Walsh,
J. R.
Bibcode: 1997A&A...326L..17L
Altcode: 1997astro.ph..7279L
Wolf-Rayet stars (WR) have been detected in the NW region of the
metal-poor starburst galaxy IZw 18. The integrated luminosity and
FWHM of the bumps at 4650 Å and 5808 Å are consistent with the
presence of a few individual stars of WC4 or WC5 type. Evolutionary
synthesis models predict few WRs in this galaxy, but only of WN
type. The presence of WC stars at such low metallicity could however
be explained by high mass loss rates, which would constrain the IMF
upper mass cut-off in IZw 18 to be higher than 80 Msun_
or alternatively favor a binary channel for WR formation. WC stars
could also explain the strong and narrow HeII 4686Å emission line
which peaks co-spatially with the WR bump emission, as suggested by
Schaerer (1996ApJ...467L..17S). This detection shows that WR stars,
even of WC type, are formed at metallicities below 1/40th solar.
Title: The O/H distribution in the transition Magellanic galaxy
NGC 1313
Authors: Walsh, J. R.; Roy, J. -R.
Bibcode: 1997MNRAS.288..726W
Altcode: 1997astro.ph..5031W
Multifibre emission-line spectrophotometry of 33 H ii regions and
three diffuse interstellar medium positions is presented for the
barred Magellanic galaxy NGC 1313. The H ii regions show a fairly
narrow range of thermal conditions characteristic of high- excitation
nebular gas. Electron temperature was directly determined in four of
the H ii regions. The global O/H abundance distribution appears very
flat across the disc at 12+log O/H~8.4+/-0.1, the bar regions possibly
having abundances higher by 0.2 dex than the outer disc. NGC 1313 is
the highest mass barred galaxy known not to have any radial abundance
gradient. The key role of the bar on the abundance distribution in
disc galaxies is revised.
Title: The abundance gradient of NGC 1365: evidence for a recently
formed bar in an archetypal barred spiral galaxy?
Authors: Roy, J. -R.; Walsh, J. R.
Bibcode: 1997MNRAS.288..715R
Altcode: 1997astro.ph..5032R
Emission-line optical spectrophotometry is presented for 55 H ii
regions in the prominent southern barred spiral galaxy NGC 1365. Nebular
diagnostic diagrams such as [N ii]/[O ii] and [S ii]/[O ii] versus ([O
ii]+[O iii])/Hβ show that the H ii regions of the barred galaxy have
the same range of physical conditions as found in non-barred late-type
galaxies. Extinction is moderately high across the disc and there is
evidence for a slight trend of extinction with galactocentric distance;
the logarithmic extinction at Hβ falls from about c(Hβ)=1.2 in the
centre to 0.6-0.8 in the outer regions. The global O/H distribution has
a moderate gradient of ~-0.5dex rho^-1_0 (~-0.02dex kpc^-1) consistent
with the known trend between the slope of the abundance gradient and the
strength of the bar. A break is seen in the O/H gradient just beyond
the -4/1 resonance, the gradient being moderately steep at ~-0.8dex
rho^-1_0 (-0.05dex kpc^-1) inside this resonance, and flat beyond
rho/rho_0≯0.55. The abundance distribution is compared with another
barred spiral galaxy, NGC 3359, and with that of two well-sampled
normal spiral galaxies, NGC 2997 and M 101. The possibility that
the bar formed recently in NGC 1365 is considered. The difficulties
encountered in performing spectrophotometry with fibre optics are
discussed and shown not to be insurmountable.
Title: The Ionized Gas in the Aftermath of a Starburst: The Case of
NGC 1569
Authors: Devost, Daniel; Roy, Jean-René; Drissen, Laurent
Bibcode: 1997ApJ...482..765D
Altcode:
Results from multislit optical spectroscopy of 16 H II regions and
deep Hα imaging of the amorphous galaxy NGC 1569 are presented. The
extinction across the main body of the galaxy, as derived from
the Balmer Hα/Hβ line ratio, indicates that most of the observed
extinction is taking place in our own Galaxy; the latter amounts to
(AV)local = 1.61 +/- 0.09, while the extinction
due to NGC 1569 is (AV)intrinsic = 0.65 +/-
0.04. The electron temperature was measured in three H II regions using
the [O III] λ4363 line. The O/H distribution shows no gradient along
the main axis of the galaxy, which is consistent with the behavior
observed in other low-mass galaxies. The average metal abundance is
12 + log O/H = 8.26, with little scatter, suggesting, on one hand,
that mixing mechanisms are very efficient throughout the main body
of the galaxy, or, on the other, that the most recent nucleosynthetic
products are hiding in a hot coronal gas phase. Up to 20% +/- 4% of the
global Hα emission originates from the faint diffuse halo component
surrounding the main body of NGC 1569. We explore the possibility that
runaway OB stars that are due to cluster ejection and associated with
the burst of supernovae which ended ~5 × 106 yr ago could
be responsible for most of the ionization of the halo gas.
Title: Hubble Space Telescope Faint Object Spectroscope Spectroscopy
of Localized Chemical Enrichment from Massive Stars in NGC 5253
Authors: Kobulnicky, Henry A.; Skillman, Evan D.; Roy, Jean-René;
Walsh, J. R.; Rosa, Michael R.
Bibcode: 1997ApJ...477..679K
Altcode:
Optical and ultraviolet spectroscopy obtained with the Hubble Space
Telescope Faint Object Spectrograph at three locations in the central
H II complex of the amorphous starburst galaxy NGC 5253 confirms an
apparent area of enhanced nitrogen abundance seen in ground-based
studies. At two positions, N appears enhanced by a factor of 3
[log (N/O) = -0.85] compared to a third location 50 pc away where
the measured N abundance is typical of metal-poor galaxies [log
(N/O) = -1.30]. No other elemental species shows spatial abundance
fluctuations, including C as measured from the C III] λλ1907, 1909 Å
emission lines. Extinction to the emission-line regions is quite low
(AV = 0.25), and we rule out reddening uncertainties as
the cause of the apparent N enhancement. Comparison of the observed
ionic fractions to predictions of photoionization models shows that
ionization uncertainties cannot be responsible for the anomalously high
N/O ratio. These findings require the existence of a N production
mechanism that is decoupled from C and O production. Although
the high N/He enrichment ratio is consistent with that expected
from non-Type I planetary nebulae (PNs), the localized nature of
the enrichment, the large number of PNs (150-500), and the long
timescales (109 yr) required make this explanation highly
unlikely. Given the proximity of the N overabundance to a very young,
heavily obscured star cluster, we attribute the N excess to recent
``pollution'' from massive stars. Plausible N enrichment scenarios
involve O star winds, He-deficient W-R star winds, and/or ejection
events from luminous blue variables. If the N enrichment is due to
localized pollution from the winds of W-R stars observed in the burst,
then an accompanying He enrichment of 40% ought to be observed, but we
are able to rule out He enhancements at the 2 σ level at both locations
showing N enhancement. We propose that if the N-rich wind or ejecta is
incorporated into self-gravitating clumps of molecular gas, and if the
106 yr old clusters of massive stars in starburst galaxies
are precursors of globular clusters, then N-overabundant halo and
globular cluster stars in the Galaxy may owe their chemical peculiarity
to similar N-enrichment episodes early in the history of the Milky Way.
Title: Induced star formation and chemical enrichment in NGC 5253
Authors: Kobulnicky, Chip; Skillman, Evan; Roy, Jean-Rene; Walsh,
J. R.; Rosa, Michael R.
Bibcode: 1997AIPC..393..586K
Altcode: 1997sfnf.conf..586K
New VLA neutral hydrogen maps for the amorphous starburst galaxy NGC
5253 are presented, along with HST optical and UV spectroscopy of the
central HII regions. The data appear to show an infalling HI stream on
the SE side of the galaxy which may be responsible for triggering the
young burst of star formation. The central HII region exhibits a 300%
nitrogen overabundance compared to the surrounding gas, and we propose
that recent chemical pollution from massive stars is responsible.
Title: A New Luminous Blue Variable in the Giant Extragalactic H II
Region NGC 2363
Authors: Drissen, Laurent; Roy, Jean-René; Robert, Carmelle
Bibcode: 1997ApJ...474L..35D
Altcode:
We report the discovery of an erupting luminous blue variable (LBV)
star in the giant H II region NGC 2363, the most massive star-forming
region in the Magellanic irregular galaxy NGC 2366. This LBV, presently
the visually brightest star in the galaxy (MV ~ -10.2),
was first noticed in Hubble Space Telescope Wide Field Planetary
Camera 2 images taken in 1996 January. An archival search allowed
us to determine the onset of the present outburst. This star was not
visible in 1991 nor 1992, but appeared in late 1993. In early 1995,
it became the brightest star in the galaxy. The spectrum of the LBV
displays a strong Hα emission line, as well as blueshifted absorption
lines of He I. Based on observations with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by AURA, Inc., under NASA contract NAS5-26555.
Title: Une supernova découverte au CFH: SN 1996D
Authors: Drissen, L.; Robert, C.; Dutil, Y.; Roy, J. -R.
Bibcode: 1997BCFHT..36...13D
Altcode:
No abstract at ADS
Title: Localized chemical enrichment in NGC 5253 from Hubble Space
Telescope FOS spectroscopy.
Authors: Kobulnicky, C.; Skillman, E. D.; Roy, J. -R.; Rosa, M. R.;
Walsh, J. R.
Bibcode: 1996BAAS...28..838K
Altcode:
No abstract at ADS
Title: Localized Chemical Enrichment in NGC 5253 from Hubble Space
Telescope FOS Spectroscopy
Authors: Kobulnicky, C.; Skillman, E.; Roy, J. -R.; Rosa, M.; Walsh,
J. R.
Bibcode: 1996AAS...188.1008K
Altcode: 1996BAAS...28R.838K
The central HII region in the amorphous galaxy NGC 5253 represents
the best evidence that massive star clusters contribute significantly
to the short-term, localized chemical enrichment of the surrounding
interstellar medium. Ground based observations (Welch, 1970, ApJ, 161,
821; Walsh & Roy, 1989, MNRAS, 239, 297) revealed that in an 80
pc diameter region coinciding with strong Wolf-Rayet star features,
the nebular abundance of N is elevated by 400% compared to galaxies
of similar metallicity (12+log(O/H) = 8.15, Z=0.20 Z_sun). From
Hubble Space Telescope FOS spectroscopy, we confirm the elevated
N abundances (log(N/O)= -0.90) at two locations in the central HII
region. Interestingly, we find that He abundances are consistent with
(He/H) ~ 0.08, typical of low-metallicity galaxies. Measurements of
the C III] lambda 1909 Angstroms emission line, in conjunction with
[O III] lambda 5007 Angstroms, yield log(C/O) = -0.68, typical of
low-metallicity galaxies (Garnett et al. 1995, ApJ, 443, 64) and
consistent with no C enrichment. As N and C production are thought to
be produced mostly in intermediate and low-mass stars respectively, the
lack of C enrichment in NGC 5253 suggests two possibilities. Either 1)
massive stars are a significant source of primary N, and the N--rich and
He--rich Wolf-Rayet star winds are responsible for the observed elevated
abundances, or, 2) the elevated N is due to secondary production in
intermediate mass stars, and N production is effectively de-coupled from
C production. This latter possibility also requires an overproduction
of N relative to O which must be explained in terms of an unusual star
formation history or IMF in NGC 5253.
Title: The O/H Distribution in the Low-Mass Galaxies NGC 2366 and
NGC 4395
Authors: Roy, Jean-Rene; Belley, Julien; Dutil, Yvan; Martin, Pierre
Bibcode: 1996ApJ...460..284R
Altcode:
Results of a spectrophotometric survey in the magellanic barred galaxy
NGC 2366 and in the small weakly barred spiral galaxy NGC 4395,
employing imaging spectrophotometry with narrow-band interference
filters in the lines of Hα, Hβ, [O III] λ5007 and [N II] λ6584, are
presented. The use of [O III]/Hβ as an abundance indicator is assessed;
it is shown that for the probable range of the physical properties of
the H II regions in NGC 2366 and NGC 4395, [O III]/Hβ may not give
reliable estimates of O/H abundances in the interstellar gas in these
two low-mass galaxies. Instead we use [NII]/[O III], which is more
dependable at relatively low abundances. The derived mean levels of
O/H (+/-1 σ dispersion) in NGC 2366 and NGC 4395 are 12 + log O/H =
8.19 +/- 0.14 and 8.33 +/- 0.25, respectively; the global gradients
of both galaxies are flat. Mechanisms which could explain the absence
of abundance gradients in low-mass and irregular galaxies are explored.
Title: Supernova 1996D in NGC 1614
Authors: Drissen, L.; Robert, C.; Dutil, Y.; Roy, J. -R.; Filippenko,
A. V.; Cappellaro, E.; Patat, F.
Bibcode: 1996IAUC.6317....2D
Altcode: 1996IAUC.6317R...1D; 1996IAUC.6317B...1D
L. Drissen, C. Robert, Y. Dutil, and J.-R. Roy, Departement de Physique,
Universite Laval, report the discovery of a supernova on an image
and spectrogram obtained at the Canada-France-Hawaii telescope on
Feb. 9. A preliminary inspection of the partially- calibrated data by
A. V. Filippenko (University of California at Berkeley) suggested that
this might be a type-Ic supernova. SN 1996D is located in a spiral arm,
about 6".6 east of the bright nucleus of NGC 1614 (R.A. = 4h34m.0,
Decl. = -8o35', equinox 2000.0). This new source is not visible in
previous images, the latest known being a Hubble Space Telescope WFPC2
image (F606W) collected on 1994 Dec. 11. E. Cappellaro, Osservatorio
Astronomico di Padova; and F. Patat, European Southern Observatory
(ESO) report: "On Feb. 18.0 UT, we observed SN 1996D with the 2.2-m
ESO telescope (+ EFOSC2). Based on a low-resolution (3.5 nm) spectrum
(range 380-900 nm), we confirm that this is indeed a type-Ic supernova
near maximum light. The most prominent features are O I at 777.3 nm and
the Ca II infrared triplet, both showing a P-Cyg profile and indicating
an expansion velocity of about 8000 km/s. The recession velocity derived
from the narrow H-alpha and S II emissions of the underlying H II
region is 4750 km/s. Preliminary photometry gives V = 18.2, V-R = +0.7."
Title: Abundance Distributions in Barred Galaxies
Authors: Roy, J. -R.
Bibcode: 1996ASPC...91...63R
Altcode: 1996IAUCo.157...63R; 1996baga.conf...63R
No abstract at ADS
Title: NGC 2363
Authors: Drissen, L.; Roy, J. -R.; Robert, C.
Bibcode: 1996IAUC.6294....1D
Altcode: 1996IAUC.6294A...1D
L. Drissen, J.-R. Roy and C. Robert, Departement de Physique, Universite
Laval, Quebec, communicate: "We report the discovery of an unusually
bright new object in the middle of the giant H II region NGC 2363, based
on Hubble Space Telescope WFPC2 images obtained on Jan. 8. Preliminary
reductions indicate V = 17.95, B-V roughly 0 for the new object. This
point source, which was then the brightest star in NGC 2363 (absolute
V about -10.0), was not visible on groundbased CCD images obtained in
Jan. 1991 and Oct. 1992 at the Canada-France-Hawaii telescope; although
crowding is severe in groundbased images, no point source brighter than
V about 22 was visible at that location. WFPC2 images indicate that
this object is a strong H alpha point source, surrounded by a small
(radius 0".09, or 1.5 pc at a distance of 3.5 Mpc) H alpha shell. We
suspect that this object is a Luminous Blue Variable star in eruption
(a la Eta Car). The coordinates of this star, from our WFPC2 images,
are R.A. = 7h28m43s.4, Decl. = +69d11'24" (equinox 2000.0). This is 0".5
west and 1".3 north of the 'eastern knot' of NGC 2363 (Fig. 2 in Drissen
et al. 1993, A.J. 106, 1460). NGC 2363 is the brightest star-forming
region in the Magellanic irregular NGC 2366, a member of the M81 group."
Title: Large Scale Transport and Mixing in the Interstellar Medium
of Gas-Rich Galaxies.
Authors: Roy, J. -R.
Bibcode: 1996ibms.conf..187R
Altcode:
No abstract at ADS
Title: The Stellar Content of Giant HII Regions in NGC 2403
Authors: Drissen, L.; Roy, J. -R.
Bibcode: 1996ASPC...98..406D
Altcode: 1996fstg.conf..406D
No abstract at ADS
Title: Interactions Between a Jet and Molecular Clouds in Spiral
Galaxy NGC 4258
Authors: Plante, R. L.; Roy, J. -R.; Lo, K. Y.; Martin, P.; Noreau, L.
Bibcode: 1995ADIL...RP...05P
Altcode:
The SABbc spiral galaxy NGC 4258 is known for its anomalous arms
believed to be indicative of nuclear activity, possibly resulting
in twin jets. In this study, we compare radio images of CO (J=1-0)
emission from the galactic nucleus with optical images of H-alpha
and red continuum. The CO emission is found to arise from a ring-like
structure, and the bulk of the detected CO appears to coincide with
dust features seen in optical continuum. The CO distribution also
appears to confine the inner part of the anomalous H-alpha arm in NGC
4258. To account for the unusual velocity field of the CO emission,
we obtain a simple kinematic model for the motion of the molecular
gas that superimposes expansion away from the galaxy's center on top
of elliptical motion. We identify a feature in the CO emission whose
motion is perturbed with respect to this model and suggest that this
deviation is evidence for a deflection of the line-emitting jet by a
dense molecular cloud.
Title: NGC 5253 Starburst as a Laboratory for Enrichment Processes
Authors: Roy, Jean-Rene
Bibcode: 1995hst..prop.6001R
Altcode: 1995hst..prop.2474R
The nearby starburst in NGC 5253 presents a unique snapshot of the
short stage of element enrichment and an unprecedented opportunity
to study the interaction between evolving massive stars and the
interstellar medium. We propose to observe NGC 5253 with FOS to: {i}
determine the carbon abundance near a region of enhanced nitrogen
found from the ground to be associated with Wolf-Rayet stars, and {ii}
to study the stellar population in the central starburst knots and
to model their age and IMF in order to relate the stellar properties
to the ISM enrichment. HST provides the long wavelength coverage
to allow determination of element abundances, IMF and starburst age
from stellar signatures, together with the high spatial resolution to
measure change over arcsec scales. The proposed observations should
result in a fundamental understanding of the link between starbursts
and enrichment mechanisms of relatively low metallicity gas.
Title: The Oxygen Distribution in NGC 3359 or a Disk Galaxy in the
Early Phase of Bar Formation
Authors: Martin, Pierre; Roy, Jean-Rene
Bibcode: 1995ApJ...445..161M
Altcode:
Monochromatic imaging in the nebular lines Hα, Hβ, [O III] λ5007,
and [N II] λ6584 has been performed on 77 H II regions from 0.13R_eff_
to 2.04R_eff_ in the barred spiral galaxy NGC 3359. The galaxy shows
several bright H II regions along its bar; according to numerical
simulations of barred galaxies, this morphology suggests that the barred
structure was formed recently (within 1 Gyr). The O/H abundance gradient
across the disk of NGC 3359 was derived from the abundance indicators
[O III]/Hβ and [N II]/[O III] calibrated by Edmunds & Pagel
(1984). A break in the slope of the O/H gradient is clearly seen near
the corotation radius (~4 kpc). The inner O/H gradient is steep [{DELTA}
log (O/H)/{DELTA}R = -0.0701 +/- 0.010 dex kpc^-1^] and the O/H scatter
is moderate (+/-0.10 dex); outside the corotation, the gradient appears
flat [{DELTA} log (O,/H)/ {DELTA}R = 0.006 +/- 0.018 dex kpc^-1^] and
the spread in O/H is significantly larger (+/-0.2 dex) than in the
inner parts. This result is in agreement with recent simulations of
barred spiral galaxies: star formation inside the corotation radius is
enhanced by large amounts of gas driven by radial flows induced by the
bar and contributes to maintain the initial O/H gradient; in the outer
parts, strong gas mixing induced by flows directed outward and along
the spiral arms produces a flattened gradient (e.g., Friedli, Benz,
& Kennicutt 1994). Based on previous H I kinematics data on NGC
3359 and results of numerical models of barred galaxies, we show that
flows along the spiral arms have had enough time to wiped out the O/H
gradient outside the corotation as far as at least 9.5 kpc. However,
the presence of large azimuthal abundance fluctuations in the outer
disk indicates that the age of the bar is ~4 x 10^8^ yr. The steep
inner O/H gradient is also discussed, and we suggest that the present
star formation inside the corotation minimizes the dilution of the
chemical composition by gas flows. Finally, a brief analysis of the
global O/H gradients in disk galaxies with bars showing different
star-forming activity is performed.
Title: Optical Continuum Signature of the Jet in the Spiral Galaxy
NGC 4258
Authors: Dutil, Yvan; Beauchamp, Dominique; Roy, Jean-Rene
Bibcode: 1995ApJ...444L..85D
Altcode:
The large spiral nearby SABbc galaxy NGC 4258 has been imaged in the
optical continuum using two filters at 5320 A and 7020 A with 200
bandpasses which are free of emission lines. The color image produced
by dividing the two bandpasses reveals an elongated feature at the
location of the jet seen in the radio continuum and in Hα. The jet
seen in the optical continuum appears as a "blue" feature compared to
the galaxy bulge. We consider four possible origins for the optical
continuum signature of the jet: (1) optical synchrotron radiation,
(2) light from the invisible active nucleus scattered by interstellar
electrons or dust particles in the channel bored in the interstellar
medium by the high-energy particles of the jet, (3) continuum emission
from shocks in colliding high-velocity clumps of gas, and (4) a passive
mechanism: reduced extinction through the galaxy because of the absence
of dust in the jet. It is shown that a combination of the last two
effects may be the most likely explanation for the optical continuum
observed in the jet of NGC 4258.
Title: Dispersal and mixing of oxygen in the interstellar medium of
gas-rich galaxies.
Authors: Roy, J. -R.; Kunth, D.
Bibcode: 1995A&A...294..432R
Altcode: 1994astro.ph.10023R
Stellar and nebular abundance indicators reveal that there exists
significant abundance fluctuations in the interstellar medium (ISM)
of gas-rich galaxies. It is shown that at the present observed solar
level of O/H~6x10^-4^, abundance differences of a factor of two, such
as existing between the Sun and the nearby Orion Nebula, are many
times larger than expected. We examine a variety of hydrodynamical
processes operating at scales ranging from 1pc to greater than 10kpc,
and show that the ISM should appear better homogenized chemically than
it actually is: (i) on large galactic scales (1>=l>=10kpc),
turbulent diffusion of interstellar clouds in the shear flow of
galactic differential rotation is able to wipe out azimuthal O/H
fluctuations in less than 10^9^yr; (ii) at the intermediate scale
(100>=l>=1000pc), cloud collisions and expanding supershells
driven by evolving associations of massive stars, differential
rotation and triggered star formation will re-distribute and mix gas
efficiently in about 10^8^yr; (iii) at small scales (1>=l>=100pc),
turbulent diffusion may be the dominant mechanism in cold clouds,
while Rayleigh-Taylor and Kelvin-Helmhotz instabilities quickly
develop in regions of gas ionized by massive stars, leading to full
mixing in <=2x10^6^yr. It is suggested that the relatively large O/H
fluctuations observed in large disk galaxies may be due to retention,
in sites favored by triggered star formation, of freshly enriched ejecta
from SNR and supershells expanding in a differentially rotating disk,
plus, possibly, infall of low metallicity material from individual
clouds like high velocity clouds which splash on the disk on timescales
shorter than the local mixing time. In low-mass galaxies, stimulated
star formation is much less efficient, and the most effective mixing
mechanisms are absent; the escape of newly enriched material due to
galactic winds powered by the starburst events, the lack of large-scale
stirring, and the long dormant phase between successive star forming
episodes make possible the survival of large abundance discontinuities.
Title: Mount Mégantic Observatory, Département de Physique,
Université de Montréal, Departement de Physique, Université Laval,
Montréal, Qc H3C 3J7, Canada, Québec, Qc G1K 7P4, Canada. Report
for the period 1 Sep 1993 - 31 Aug 1994.
Authors: Roy, J. -R.; Moffat, A. F. J.
Bibcode: 1995BAAS...27..353R
Altcode:
No abstract at ADS
Title: Mixing of Heavy Elements into the Interstellar Medium of
Gas-Rich
Authors: Kunth, D.; Matteucci, F.; Roy, J. -R.
Bibcode: 1995lea..conf..118K
Altcode:
No abstract at ADS
Title: A Ring Nebula Surrounding Evolved Massive Stars in the
Post-Starburst Galaxy NGC 1569
Authors: Drissen, Laurent; Roy, Jean-Rene
Bibcode: 1994PASP..106..974D
Altcode:
Broad stellar emission lines have been detected in the optical spectrum
of a small cluster in the post-starburst galaxy NGC 1569. These lines,
He I 5876, H-alpha, and He I 6678, have a full width at half maximum
of 600 km s^-1, and are attributed to a late-type WN star. the cluster,
located in the outskirts of the galaxy, is surrounded by a large (Radius
= 30 pc) ring nebula. This detection of a Wolf-Rayet star is a direct
evidence of recent (<= 5 Myrs) massive (M_i >= 40 solar mass)
star formation in NGC 1569. (SECTION: Interstellar Medium and Nebulae)
Title: The Influence of Bars on the Chemical Composition of Spiral
Galaxies
Authors: Martin, Pierre; Roy, Jean-Rene
Bibcode: 1994ApJ...424..599M
Altcode:
Imaging spectrophotometry in the nebular lines Hα, Hβ, [O III]
λ5007 and [N II] λ6584, using narrow-band interference filters,
has been performed of 82, 55, and 79 H II regions in the barred
spiral galaxies NGC 925, NGC 1073, and NGC 4303, respectively. The
O/H abundance gradients were derived from the abundance indicators
[O III],/Hβ and [N II]/[O III], calibrated by Edmunds & Pagel
(1984). The global O/H gradients in NGC 925 [{DELTA} log (O/H)/{DELTA}R
= -0.033 dex kpc^-1^] and NGC 1073 [{DELTA} log (O/H)/{DELTA}R =
-0.048 dex kpc^-1^] are flatter than the gradients observed in normal
galaxies of the same morphological type. The abundance gradient in NGC
4303 is identical to that found in normal spiral galaxies. A comparison
is made between the O/H gradients of normal galaxies and of a sample of
galaxies showing a barred morphology. It is concluded that the global
abundance gradients of spiral galaxies with a barred structure are in
general shallower than gradients of normal galaxies. The slopes of
O/H gradients are analyzed as a function of two properties of bars:
the relative length of the bar with respect to the size of the disk,
and the bar ellipticity, defined by the axis ratio of the bar. It is
found that gradients are flatter when the length or the ellipticity
of the bar increases. This result is consistent with recent models of
radial flows. These observations indicate that large-scale mixing of
the interstellar gas occurs across the disks of barred spiral galaxies
and affects the radial distribution of elements.
Title: Dark Matter Distribution and the HI - H(alpha) Connection in
IC 2574
Authors: Martimbeau, N.; Carignan, C.; Roy, J. -R.
Bibcode: 1994AJ....107..543M
Altcode:
A detailed study of the low surface brightness late-type dwarf
spiral galaxy IC 2574 is presented. By combining data from broadband
surface photometry, narrow-band Hα imaging, and H I radio synthesis
observations, it is possible to study the structure of the stellar disk
and the properties of both the neutral and ionized gaseous components,
as well as their interaction. From the B and R photometry, an
extrapolated central surface brightness B(0)_c_ = 23.44 mag arcsec^-2^,
a scale length of α^-1^ = 2.2 kpc, and a color index <B-R> = 0.96
are derived. From the radio synthesis observations, it is possible to
trace the H I emission over ~1.8 D_25_ and to derive a rotation curve
out to ~8 kpc. This curve rises slowly, barely flattening at its end,
with a maximum rotational velocity of 67 km s^-1^. Noncircular motions
are the main source of uncertainties for r < 4'. The mass model
that best fits the data suggests a (M/L_B_)_*_ = 0.4 for the luminous
stellar disk and a core radius r_c_ = 8 kpc and a central density p_0_
= 0.0064 M_sun_ pc^- 3^ for the dark halo component. Contrary to more
massive galaxies where the luminous disk dominates in the inner parts,
the dark component dominates at all radii. This is not particular to IC
2574, but seems to be the case for many low surface brightness late-type
spirals. In this respect, the properties of the dark matter distribution
in IC 2574 are closer to what is seen in dwarf irregulars than in
massive spirals. Comparison of H I column density and velocity maps
suggests that H I holes correspond to expanding shells or rings. Most
of the H II regions are found around the rims of H I holes. The giant
northeastern H II complex is associated with a peak of H I emission; its
properties are consistent with triggered star formation resulting from
the collapse of swept-up matter in an expanding and decelerating ring.
Title: A Search for Wolf-Rayet Stars in Active Star Forming Regions
of Low Mass Galaxies: GR8, NGC 2366, IC 2574, and NGC 1569
Authors: Drissen, Laurent; Roy, Jean-Rene; Moffat, Anthony F. J.
Bibcode: 1993AJ....106.1460D
Altcode:
We report the detection, via narrow-band λ4686 filter imagery, of
possible new Wolf-Rayet stars in the most massive giant H II regions of
the irregular galaxies NGC 2366 and IC 2574. One stellar knot in the
post-starburst galaxy NGC 1569 also appears to contain a weak excess
of light at λ4686. A similar search yielded negative results in the
very low mass galaxy GR8. The strongest λ4686 excess is located close
to the secondary eastern knot in the core of NGC 2366-I (NGC 2363). If
this excess is of stellar origin, about five Wolf-Rayet stars of the
luminous late-type (WNL) can account for the excess emission. Nebular
emission wraps around this cluster in the form of a shell. The putative
Wolf-Rayet stars appear to be close to the center of the large expanding
H II bubble discovered by Roy et al. [ApJ, 367, 141(1991)]. A possible
nebular origin of the λ4686 excess is also discussed.
Title: Abundances in the starburst galaxy II ZW 40.
Authors: Walsh, J. R.; Roy, Jean-Rene
Bibcode: 1993MNRAS.262...27W
Altcode:
Low-dispersion optical imaging spectroscopy has been performed of the
starburst galaxy II Zw 40, employing the area spectroscopy system at
the Anglo-Australian Telescope. A procedure was applied to correct
for the effects of atmospheric differential refraction arising from
the large zenith distance of the observations. Maps of interstellar
reddening, electron temperature and abundances of elements (O/H, N/H,
He/H and Ne/H) were constructed. Comparisons are made with similar
maps of the amorphous galaxy NGC 5253. II Zw 40 suffers from large
intrinsic absorption due to dust, with the greater values of A_V_
being found in the northern half of the galaxy. Electron temperatures
were measured at 24 points over the bright core of the galaxy from the
[O III] 5007/4363-A line ratio. The mean value of T_e_ derived from
the integrated spectrum of the emission- line region is 12000 K, and
[O/H] = 8.25. Three points covering an area of approximately 160 X
100 pc^2^ have significantly lower T_e_ and abundances of O/H and N/H
appear higher. It is shown that the original calibration proposed by
Pagel, Edmunds & Smith for the line ratio ([0 II]+[O III])/Hβ
to derive O/H agrees with our direct measurements of O/H for the
metallicity range observed in II Zw 40 and NGC 5253. N/O is found
to be weakly inversely correlated with O/H in II Zw 40, as for NGC
5253. Various mechanisms have been explored in order to explain this
anticorrelation. Radiative recombination in the O^2+^ region is not
found to be a significant contributor to the [O II] surface brightness;
thus it cannot account for the anticorrelation. Excitation or charge
exchange reaction effects can also be excluded. The observed behaviour
of N/O in II Zw 40 and NGC 5253 is possibly due to a mix of secondary
nitrogen with primary nitrogen of unknown origin.
Title: The co-existence of spiral structure and abundance gradients.
Authors: Edmunds, M. G.; Roy, Jean-Rene
Bibcode: 1993MNRAS.261L..17E
Altcode:
Steep abundance gradients in gas-rich disc galaxies seem to require the
presence of unbarred spiral structure. Abundance gradients disappear
at the same absolute magnitude that spiral structure ceases, and are
considerably shallower in spirals showing a strong bar. This suggests
a definite link between the existence of unbarred spiral structure
and the origin of abundance gradients.
Title: The Ionized Gas in the Center and in the Bar of the Spiral
Galaxy NGC 6946
Authors: Roy, Jean-Rene; Belley, Julien
Bibcode: 1993ApJ...406...60R
Altcode:
Spectrophotometric data based on narrow-band images at Hα, Hβ,
[O III] λ5007 and [N II] λ6584 for 189 H II regions in the spiral
galaxy NGC 6946 are presented, with emphasis on the inner regions
(R <= 2.5 kpc). The properties of the ionized gas are compared
with those of the CO molecular bar. The possible influence of the bar
on the ionized interstellar gas and star formation is discussed. The
relatively high number of H II regions in the center is consistent
with an enhancement of massive star formation as revealed by infrared
and molecular observations the molecular gas bar in NGC 6946 is a
favorable environment for massive star formation. The excitation and
abundance indicators [O III] (λλ5007 + 4959)/Hβ and [N II] (λλ6584
+ 6548)/[O III] (λλ5007+4959) show an unusual behavior as a function
of galactocentric distances, and their radial trend is consistent with
a flattening of the global O/H gradient in the inner regions of NGC
6946. This may be evidence of dilution by low-metallicity gas from
outer regions due to strong radial flow along the molecular bar.
Title: Spiral structure and star formation in the galaxy NGC 6814.
Authors: Roy, J. -R.; Arsenault, R.
Bibcode: 1993AGAb....8...67R
Altcode: 1993AGAb....8...67.
No abstract at ADS
Title: "Bimodal" Star Formation in the Spiral Galaxy NGC 6814
Authors: Roy, J. -R.; Arsenault, R.
Bibcode: 1993BCFHT..28...21R
Altcode:
No abstract at ADS
Title: The Oxygen Abundance Gradient in the Barred Spiral Galaxy
NGC 4303
Authors: Martin, Pierre; Roy, Jean-Rene
Bibcode: 1992ApJ...397..463M
Altcode:
Imaging spectrophotometry in the nebular lines Hα, Hβ, [O III] λ5007,
and [N II] λ6584, using a CCD camera and narrow-band interference
filters, has been performed of 79 H II regions in the barred spiral
galaxy NGC 4303 ranging from 0.4 to 2.8 R_eff_ in galactocentric
distances. Except for the bright emission in the nuclear region,
the area within the bar radius is devoid of H II regions. The O/H
abundance gradient was derived from the abundance indicators [O
III]/Hβ and [N II]/[O III]. The global abundance gradient derived from
[O III]/Hβ corresponds to {DELTA} log (O/H)/{DELTA}R = -0.073 +/-
0.006 dex kpc^-1^, which is identical to that found in normal spiral
galaxies like NGC 628, NGC 2997, and the Milky Way, i.e., there is no
evidence of a "flatter" gradient due to the presence of a bar in NGC
4303. It is concluded that the presence of the bar has not affected
the relative distribution of elements in the disk of NGC 4303 in the
region beyond the stellar bar.
Title: Holmberg II: A Laboratory for Studying the Violent Interstellar
Medium
Authors: Puche, Daniel; Westpfahl, David; Brinks, Elias; Roy, Jean-Rene
Bibcode: 1992AJ....103.1841P
Altcode:
VLA H I observations of Holmberg II (HoII = UGC 4305 = DDO 50) at high
spatial and velocity resolution show a stunning amount of detail in
the form of H I shells and holes in its interstellar medium, similar
to features seen in the Galaxy, M31 and M33. These features range in
size from 100 to 1700 pc and show expansion velocities of typically
7 km s^-1^. Their indicative ages range from 1 X 10^7^ to 1.5 X 10^8^
yr. There is a striking correlation between Hα emission, as seen in
high quality CFHT CCD frames, and H I shells. The smaller holes tend
to be filled with Hα emission whereas for the larger H I holes the
Hα seems to be restricted to the edges. The most likely explanation
for these features is in terms of events of sequential star formation
whereby the combined effects of photoionisation, stellar winds, and
supernovae of the most massive stars shape the interstellar medium. Some
H II regions along the edges of larger shells may correspond to
secondary sites of star formation. Massive stars, possibly in clusters,
at the centers of the largest holes provide supporting evidence for the
above picture. Infall of material, although not ruled out, is not needed
to explain the overall features or large dimensions of the holes. The H
I holes in HoII are much larger than those found in more massive spiral
galaxies. This is attributed to HoII having an H I scale height of h =
625 pc rather than the more usual 120 pc. The scale height is derived
independently by measuring the velocity dispersion of the gas which
is of order 6-7 km s^-1^ and combining it with a mass model which is
derived on the basis of the H I rotation curve. This larger scale height
translates to a lower gas volume density which facilitates the expansion
of H I shells. In addition they can expand to larger dimensions before
experiencing blow-out The global H I distribution is typical of a late-
type gas rich dwarf system. The velocity field shows a rapid rise of
the rotation velocity in the inner parts and a flat rotation curve
in the outer regions out to a radius of 7.5 kpc. At large radii HoII
displays a symmetrical warp. A total H I mass of M_H I_ = 7 X 10^8^
M_sun_ and a total kinematical mass of M_total_ = 2 X 10^9^M_sun_
are derived, indicating that HoII has a large fraction of its mass
in the form of gas, about 50% when corrected for the contribution
of He. The flatness of the rotation curve at the last measured point
implies the presence of dark matter. In a few areas, mostly near H II
regions, we find peak H I brightness temperatures as high as 150-250 K,
a much higher value than in the Galaxy. The reason for the observed
brightness temperatures is not well understood. It could be due to
a different energy balance in the ISM of HoII which is linked to a
lower heavy element abundance, preventing efficient cooling, and a
strong interstellar radiation field. A simpler explanation is that
a large fraction of the neutral gas is in the warm phase such that
line-of-sight integration produces the observed peak brightnesses.
Title: The Origin of Broad Emission Lines in the Extragalactic Giant
H II Region NGC 2363
Authors: Roy, Jean-Rene; Aube, Martin; McCall, Marshall L.; Dufour,
R. J.
Bibcode: 1992ApJ...386..498R
Altcode:
High signal-to-noise long-slit spectra have been obtained of the
giant H II region NGC 2363 located in the dwarf SBm galaxy NGC
2366. A discovery of low-intensity broad spectral components (FWHM
~40 A or 2400 km s^-1^) in the bright nebular lines Hα, Hβ, and
[O III) is reported. The broad spectral components are detected over
a large spatial extent (>= 500 pc) centered on the nebula. Several
mechanisms for broadening nebular lines are explored: stellar winds,
Thomson scattering by hot gas, supernova remnants, and superbubble
blowout. All mechanisms have problems. Superbubble blowout, which is
the only known mechanism capable of accelerating interstellar gas over
such a volume of space, does not appear consistent with the physical
properties of the H II region NGC 2363 or with the nature of the host
galaxy. It is concluded that the broad nebular lines are probably due
to very high velocity gas whose origin is, at present, unknown.
Title: Abundance gradients in barred spiral galaxies
Authors: Martin, P.; Roy, J. -R.; Belley, J.
Bibcode: 1992pngn.conf..101M
Altcode:
No abstract at ADS
Title: The Abundance Gradients across the Spiral Galaxies NGC 628
and NGC 6946
Authors: Belley, Julien; Roy, Jean-Rene
Bibcode: 1992ApJS...78...61B
Altcode:
Imaging spectrophotometry in the nebular lines Hα, Hβ, [N II], and
[O III], using narrow-band interference filters and a CCD camera, has
been performed of nearly 300 H II regions in the galaxies NGC 628 and
NGC 6946. The reliability of the method for doing spectrophotometry
of H II regions is demonstrated, and several physical parameters
related to the chemistry of the galaxies are derived. Reddening,
Hβ emission equivalent widths, diagnostic line ratios [O III]/Hβ
and [N II]/[O III], and O/H abundances were measured for 130 H II
regions as far as 2.0R_eff_ in NGC 628, and for 160 H II regions as
far as 1.4R_eff_ in NGC 6946. Neither reddening nor the Hβ equivalent
widths display any trend as a function of radial distances from the
galactic centers. On the other hand, [O III]/Hβ and [N II]/[O III]
are strongly correlated with galactocentric distances; the values of
[N II]/[O III] display less dispersion at any given radius. Using
the empirical calibration of Edmunds & Pagel, O/H abundances were
calculated for all H II regions. In NGC 628, the global oxygen abundance
gradient is described by {DELTA}log(O/H)/{DELTA}R = -0.081+/-0.002
dex kpc^-1^,at an assumed distance of 7.2 Mpc; in NGC 6946(5.9 Mpc),
the global O/H gradient is given by {DELTA}log (O/H)/{DELTA}R = -0.089
+/- 0.003 dex kpc^-1^. Extrapolated central abundances are 12 + log
(O/H) = 9.20 +/- 0.01 in NGC 628, and 9.36 +/- 0.02 in NGC 6946. The
slope of the gradient is constant across the complete range of radial
distances sampled in NGC 628. In the inner parts of NGC 6946 (R <=
0.5R_eff_), the derived abundances display a large dispersion, and the
radial trend is consistent with an almost flat gradient; for R >=
0.5R_eff_ the O/H gradient is well defined and its slope is slightly
steeper than in NGC 628. The O/H abundances in the central regions of
NGC 6946 may be affected by the presence of a molecular and ionized
gas bar. Using an enlarged sample of six galaxies, where about 50 H
II regions or more were observed, various trends are investigated. The
galaxies included in the sample correspond to a relatively wide range
of luminosities; they are NGC 628, NGC 2997, NGC 6946, M33, M 101,
and the Milky Way Galaxy. The amplitudes of their global gradients
are identical within the uncertainty of about +/- 0.01 dex kpc^-1^
on gradients of individual galaxies. Claims of correlation between
the amplitudes of gradients and other global properties of galaxies
are considered at present premature until a greater number of large
samples of H II regions becomes available. The efficiency of the method
of imaging spectrophotometry is emphasized for survey programs where
limited spectral data must be obtained for a large number of objects,
such as obtaining data samples for the derivation of reliable abundance
gradients in galaxies.
Title: Découverte de Gaz Hypersonique dans la Galaxie NGC 2366
Authors: Roy, J. -R.
Bibcode: 1992BCFHT..26...16R
Altcode:
No abstract at ADS
Title: Possible Deflection of a Jet by Molecular Clouds in NGC 4258
Authors: Plante, R. L.; Lo, K. Y.; Roy, Jean-Rene; Martin, Pierre;
Noreau, Louis
Bibcode: 1991ApJ...381..110P
Altcode:
The CO (J = 1 - 0) emission from the central 1' of NGC 4258, a SABbc
spiral galaxy with a pair of anomalous arms, was mapped using the
Owens Valley millimeter-wave interferometer. The CO emission is found
to arise from a ringlike structure, and the bulk of the detected CO
appears to coincide with dust features seen in optical images. The CO
distribution also appears to confine the inner part of the anomalous
Hα arm in NGC 4258. To account for the unusual velocity field of the
CO emission, we obtain a simple kinematic model for the motion of the
molecular gas that superposes expansion away from the galaxy center on
top of the elliptical motion. We identify a feature in the CO emission
whose motion is perturbed with respect to this model and suggest that
this deviation is evidence for a deflection of the line-emitting jet
by a dense molecular cloud.
Title: HST WFC/FOC Imagery of the Irregular Galaxy GR8
Authors: Dufour, R. J.; Scowen, P. A.; Davidson, K.; Skillman, E. D.;
Roy, J. -R.; McCall, M. L.; Clayton, D. D.; Wu, C. -C.
Bibcode: 1991BAAS...23.1456D
Altcode:
No abstract at ADS
Title: Global O/H gradients in late-type spiral galaxies and possible
bar interaction for NGC 6946.
Authors: Belley, J.; Roy, J. -R.
Bibcode: 1991JRASC..85..195B
Altcode:
No abstract at ADS
Title: Etoiles Wolf-Rayet dans les Régions HII Géantes
Extragalactiques: NGC 604 et NGC 2363
Authors: Drissen, L.; Moffat, A.; Roy, J. -R.
Bibcode: 1991BCFHT..25...15D
Altcode:
No abstract at ADS
Title: Is NGC 4631 a Barred Spiral Galaxy?
Authors: Roy, Jean-Rene; Wang, Jianguo; Arsenault, Robin
Bibcode: 1991AJ....101..825R
Altcode:
High and low dispersion optical spectra of the giant H II region
CM 67 near the center of the edge-on galaxy NGC 4631 have been
obtained. Comparisons are made with radio observations to suggest the
existence of a large bar in NGC 4631. Region CM 67 is shown to coincide
in position with the eastern- most peak of a triple radio-continuum
source. It also corresponds very closely with a giant molecular cloud
in the CO position-velocity diagram. It is concluded that the optical,
nonthermal radio continuum, and CO line emission originate from the
same volume of gas. The H II region is typical of high excitation
objects, with a ratio [OIII]/Hβ=2.8+/-0.11 normally found in H II
regions located at large galactocentric distances. We suggest that CM
67 represents the tip of a bar which has a length of several Kpc.
Title: Superbubble Blowout in the Giant H II Region NGC 2363?
Authors: Roy, Jean-Rene; Boulesteix, J.; Joncas, Gilles; Grundseth, B.
Bibcode: 1991ApJ...367..141R
Altcode:
The velocity field of the giant H II complex NGC 2363 in the SBm galaxy
NGC 2366 has been mapped in the [O III] λ 5007 A line using a scanning
Fabry-Perot interferometer. The [O III] line profiles correspond to
symmetrical and single component profiles in most of the nebulae
of NGC 2366, except in the bright core of the giant H II NGC 2363
where strong splitting of the [O III] line occurs. This splitting is
consistent with a bubble 200 pc in diameter expanding with a velocity
of 45 km s^-1^. The total kinetic energy of the bubble is 2 x 10^52^
ergs; the kinematic age of the bubble is less than or equal to 2 x 10^6^
yr. The bubble could be produced by the sole action of combined stellar
winds from the central clusters of OB stars. A well- defined sector,
150 pc wide, of the H II complex originating at the bubble shows
systematic receding velocities; it is suggested that this region acts
as a vent through which gas escapes into the halo of the galaxy. Large
Hα shells are observed in the surroundings of NGC 2363. There is also
evidence for a very broad and low-intensity [O III] high-velocity (~
1000 km s^-1^) component associated with the bubble.
Title: Bulles de Gaz Ionisé Balayées par des Vents Stellaires dans
la Galaxie Spirale NGC 628
Authors: Arsenault, R.; Belley, J.; Roy, J. -R.
Bibcode: 1991BCFHT..24...13A
Altcode:
No abstract at ADS
Title: Large-scale formation of massive stars in the spiral galaxy
NGC 4321.
Authors: Arsenault, R.; Roy, J. -R.; Boulesteix, J.
Bibcode: 1990A&A...234...23A
Altcode:
Fabry-Perot observations at Hα of the Virgo spiral galaxy NGC
4321 are presented. They were obtained using a scanning Fabry-Perot
interferometer at the Canada-France-Hawaii Telescope. Luminosities,
diameters and velocity widths have been measured for 127 giant H
II regions in the galaxy. The integral diameter function is well
described by an exponential function and the power index of the
luminosity function is 1.38. The population of the 31 H II regions
with the highest surface brightness in NGC 4321 reproduces the known
correlations observed for the first-ranked H II regions in galaxies
between luminosities, diameters and velocity widths. There is also a
correlation between the H I luminosity of these regions and the product
of the epicyclic frequency times the square of the velocity width when
this width has been corrected for large scale kinematical effects. These
relations do not appear to apply to the lower surface brightness H II
regions. It is suggested that the formation rate of massive stars is
a function of two parameters of the large scale interstellar medium:
density (gas supply) and velocity dispersion (rate of shear). Key word;
interstellar medium: H II regions: general - interstellar medium:
kinematics and dynamics of - galaxies: individual
Title: Area Spectroscopy and Correction for Differential Atmospheric
Refraction
Authors: Walsh, J. R.; Roy, J. R.
Bibcode: 1990ESOC...34...95W
Altcode: 1990daan.work...95W
No abstract at ADS
Title: The optical jet of the galaxy NGC 4258.
Authors: Martin, P.; Roy, J. -R.; Noreau, L.; Lo, K. -Y.
Bibcode: 1989JRASC..83..300M
Altcode:
No abstract at ADS
Title: The blowout of the giant H II region NGC 2363.
Authors: Roy, J. -R.; Boulesteix, J.; Joncas, G.; Grundseth, B.
Bibcode: 1989JRASC..83R.294R
Altcode:
No abstract at ADS
Title: The Optical Jet of the Galaxy NGC 4258: Interaction with the
Interstellar Medium
Authors: Martin, Pierre; Roy, Jean-Rene; Noreau, Louis; Lo, K. Y.
Bibcode: 1989ApJ...345..707M
Altcode:
Monochromatic Hα and red continuum images, as well as high-resolution
aperture synthesis ^12^CO maps, were obtained in order to study the
optical jet of the spiral galaxy NGC 4258. The jet morphology shows
strong interaction with the ambient interstellar medium. The optical
emission of the jet is due to line emission arising possibly from gas
of the ambient interstellar medium which has been entrained and shocked
by the radio-emitting gas. The jet near the center is resolved and
has a width of ~ 200 pc. The CO observations show two clouds on each
side of the nucleus; these clouds outline a channel, and the Hα jet
falls right into this channel. These observations are consistent with
the jet being in or making a small angle with the galaxy plane. It
is suggested that the channel represents a tunnel bored by energetic
material and that jet activity in NGC 4258 has been intermittent in
the recent past. The interstellar medium may play an important role
in making jets detectable optically and in shaping their forms.
Title: Optical spectroscopic and abundance mapping of the amorphous
galaxy NGC 5253.
Authors: Walsh, J. R.; Roy, Jean-Rene
Bibcode: 1989MNRAS.239..297W
Altcode:
Imaging spectroscopy at low spectral resolution of the composite
elliptical starburst galaxy NGC 5253 has been obtained with the
Anglo-Australia Telescope, RGO spectrograph and ASPECT slit scanning
software. over a region 16 by 48 arcsec^2^ (~160 by 470 pc^2^)
the emission line and continuum variations have been mapped at
high signal-to-noise ratio. As for other galaxies which have been
spectroscopically mapped with the same technique, point-to-point
fluctuations in extinction and line ratios greater than the errors
are measured. Ten regions have been defined over the mapped area,
four of which correspond to bright knots in a broad band image, and
the remainder to knots or points of inflection in broad band or H{BETA}
maps. The spectra of these ten regions are analyzed. The low metallicity
and corresponding high electron temperature, T_e_, of the complex
has enabled the [O III] 4363 A line to be well measured at 38 points
in the maps and in six of the defined regions. The electron density,
N_e_, has been measured from the [S II]6716/6731 A line ratio. From
T_e_, and N_e_, the abundances of He^+^, O, N and Ne have been mapped
over the bright core of the region and determined six of the defined
regions. The only atomic species showing marked spatial fluctuation
is nitrogen, and this is elevated in the central region (~60 pc in
diameter) by a factor of 1.8 with respect to the mean N abundance
of the surroundings. This enriched region is also associated with a
broad 4656 A feature, indicating the presence of Wolf-Rayet stars,
probably of WN type, strong blue stellar continuum and a 105 km s^-1^
wing to the Hα profile observed with an echelle spectrograph. It is
found that He^+^/H correlates better with N/O than with N/H for pixels
in the central region with enhanced N/H abundance. The correlation
is consistent with that expected if the He and N are produced by WR
star winds. Comparison with published IUE fluxes shows a high carbon
abundance with [C/O]~0.10, suggesting that WC stars may have also been
present in the starburst.
Title: The Abundance Gradient across the Galaxy NGC 2997
Authors: Walsh, J. R.; Roy, Jean-Rene
Bibcode: 1989ApJ...341..722W
Altcode:
The fiber optics coupling aperture-plate system (FOCAP) of the
Anglo-Australian Observatory was used to obtain low-dispersion spectra
of 49 H II regions across the galaxy NGC 2997. Problems with employing
fiber optics for spectrophotometry are discussed. Correlations between
line ratios used as diagnostics for physical conditions and abundances
in H II regions are identical to those found by McCall, Rybski, and
Shields for a large number of giant H II regions in 26 galaxies. The
O/H radial abundance gradient in NGC 2997 was derived using the
calibration of the index ([O II] + [O III])/Hβ. The gradient and the
mean metallicity of NGC 2997 are comparable to those of M51. There
is significant dispersion in ([O 1I] + [O II])/Hβ and [O III]/Hβ at
any given galactocentric distance. No N^+^/O^+^ gradient is observed,
and the mean value of this ratio is identical to that of Galactic H
II regions.
Title: The Structure of Giant Extragalactic H II Regions in NGC 1365,
1566, and 2997
Authors: Roy, Jean-Rene; Belley, Julien; Walsh, J. R.
Bibcode: 1989AJ.....97.1010R
Altcode:
Optical spectroscopic mapping has been performed of chains of H II
regions and complexes in the barred spiral galaxy NGC 1365, the normal
spirals 1566, 2997, and the amorphous galaxy NGC 5253. A comparison
of the spatial behavior of the line ratios between the galaxies is
presented. The line ratios [N II]/[O II], [S II]/[O II], and ([O II] +
[O III])/Hβ vary significantly from pixel to pixel. The amplitude of
pixel-to-pixel line fluctuations is highest for line ratios involving
[O II] and [0 III] and is smallest for the absorption Anu_
derived from Hα/Hβ, for [N II]/Hα, [S II]/Hα, and [N II]/[S II]. The
amplitudes of line ratio fluctuations increase with galactocentric
distances in NGC 2997; this trend is marginal in the weakly barred
galaxy NGC 1566 and non-existent in the barred spiral NGC 1365. The
line ratio fluctuations are ascribed to varying density distributions
for electrons and the various ions producing different line ratios
especially for lines originating from different nebular regions. The
radial increase of the amplitudes of line ratio fluctuations in NGC
2997 is suggested as due to the changing density distribution within
nebulae with galactocentric radius.
Title: A circumnuclear ring of enhanced star formation in the spiral
galaxy NGC 4321.
Authors: Arsenault, R.; Boulesteix, J.; Georgelin, Y.; Roy, J. -R.
Bibcode: 1989woga.conf..373A
Altcode:
No abstract at ADS
Title: The Shaping of the Optical Jet of the Galaxy NGC 4258
Authors: Martin, P.; Roy, J. -R.; Noreau, L.; Lo, K. -Y.
Bibcode: 1989LNP...350..359M
Altcode: 1989IAUCo.120..359M; 1989sdim.conf..359M
Hα+[NII] and red continuum CCD images as well as high resolution
aperture synthesis CO maps were obtained in order to study the optical
jet of the barred spiral galaxy NGC 4258. The CO observations show two
clouds near the center of the galaxy; these clouds outline a channel
and the Hα jet follows this channel. The observations are consistent
with the jet being in or making a small angle with the galaxy plane. It
is concluded that the interstellar medium may play an important role
in making jets detectable optically and in shaping their forms.
Title: Imaging spectroscopy of HII regions in the barred spiral
galaxy NGC 1365.
Authors: Roy, Jean-Rene; Walsh, Jeremy R.
Bibcode: 1988MNRAS.234..977R
Altcode:
Imaging spectroscopy at low spectral resolution of the northwestern
arm of the barred spiral galaxy NGC 1365 has been obtained with
the RGO spectrograph using the ASPECT system of the Anglo-Australian
Telescope. An area of 120x21 arcmin^2^ was mapped spectroscopically. The
line ratios used as abundance indicators vary very little along the
northwestern spiral arm; this is consistent with earlier suggestions
that a bar may act to homogenize abundances in galaxies. The correlation
between the abundance indicators [O III]/[N II] and ([O II]+[O III])/Hβ
is much tighter than in any of the three galaxies (NGC 1566, 2997 and
5253) that we have mapped so far.
Title: Multi-Object Spectrophotometry of HII Regions in the Galaxy
NGC2997
Authors: Roy, J. R.; Walsh, J. R.
Bibcode: 1988JRASC..82..280R
Altcode:
No abstract at ADS
Title: Correlations between integrated parameters and H-alpha velocity
widths in giant extragalactic HII regions : a new appraisal.
Authors: Arsenault, R.; Roy, J. -R.
Bibcode: 1988A&A...201..199A
Altcode:
Investigations of relationships between diameters (or luminosities)
and velocity widths of Hα line profiles in giant extragalactic H
II regions (GEHR) have firmly established that these parameters are
correlated. However, three independent studies on the subject disagree
on the slopes of these relations. It is shown that all measurements
of the velocity width of integrated Hα profiles of GEHRs are
entirely consistent. Discrepancies in the relations are explained by
different samples, and use of different parameters such as distances
to galaxies and diameters of GEHRs. Assembling all observations of
Hα velocity widths, new values of slopes and zero-points are derived
for the relations between luminosities (or diameters) and velocity
widths. Comparisons are made with values given by different mechanisms
predicting the scaling of supersonic motions with their linear sizes
in nebulae.
Title: A circumnuclear ring of enhanced star formation in the spiral
galaxy NGC 4321.
Authors: Arsenault, R.; Boulesteix, J.; Georgelin, Y.; Roy, J. -R.
Bibcode: 1988A&A...200...29A
Altcode:
Imaging Fabry-Perot spectroscopy at H-alpha wavelength has been obtained
on the spiral galaxy NGC 4321. This provides an H-alpha image of the
galaxy, a 656.3 nm continuum image and the H-alpha velocity field of
the ionized gas in NGC 4321. The nuclear region of this galaxy shows a
peculiar two-lobe structure in H-alpha light, in the inner 1.5 kpc. It
is proposed that the double-lobe feature is a ring of enhanced star
formation located between the two Inner Linblad Resonances (ILR). The
orbits of the gas clouds at such radii (the ILRs are located at 0.35
and 1.1 kpc) are strongly perturbed, increasing the collision rate
between the gas clouds, which in turn, induces star formation. This
kind of association of star forming regions and ILRs suggests that
star formation is linked to the dynamical behavior of the galaxy.
Title: Hubble's The Use of Giant Extragalactic HIl Regions as Distance
Indicator: New Results from a Catalog of HII Regions in the Galaxy
NGC 4321
Authors: Arsenault, R.; Boulesteix, J.; Georgelin, Y.; Roy, J. -R.
Bibcode: 1988ASPC....4..303A
Altcode: 1988egds.symp..303A
A comprehensive set of observations has been obtained on the spiral
galaxy NGC 4321 (M100) at the CFHT using CIGALE, a Fabry-Perot
interferometer coupled with a photon counting camera. Those observations
have been used to get H-alpha fluxes, H-alpha diameters and velocity
width for 108 HII regions in M100. Those parameters show no correlation
between diameter and velocity width nor between flux and velocity width.
Title: Imaging spectrophotometry of a chain of giant H II regions
in the galaxy NGC 2997.
Authors: Roy, Jean-Rene; Walsh, Jeremy R.
Bibcode: 1987MNRAS.228..883R
Altcode:
An area of 120arcsec×16arcsec of the northern arm of the spiral
galaxy NGC 2997 was scanned with the slit of the RGO spectrograph
using the ASPECT system of the Anglo-Australian Telescope. 530 spectra
were obtained. Monochromatic images and diagnostic diagrams of line
ratios based on spectral lines at Hα, Hβ, [O II] 3727 Å, [O III]
5007 Å, [N II] 6584 Å and [S II] 6717 - 30 Å, and continua at 3580
Å and 5400 Å are constructed. Correlations are found between the
absorption AV and the oxygen abundance index ([O II]+[O
III])/Hβ indicating that the hotter stars are imbedded in more dust
than the later-type stars. Reddening also arises from external dust;
this dust is closely associated with the H II regions, because the
stellar continuum is found to be less affected by reddening. Synthesis
of the spiral arm stellar continuum was performed and the spectral
signature of early-type stars was clearly detected in the H II regions.
Title: Nitrogen Abundances in the Amorphous Galaxy NGC 5253
Authors: Walsh, Jeremy R.; Roy, Jean-Rene
Bibcode: 1987ApJ...319L..57W
Altcode:
The central complex of ionized gas in the amorphous galaxy NGC 5253
was scanned with the slit of the RGO spectrograph using the imaging
spectroscopy system of the Anglo-Australian Telescope. Monochromatic
images corresponding to several nebular lines were obtained with a
spatial resolution of 2.3 x 1.3 sq arcsec (1 pixel). The very high
signal-to-noise ratio of the spectra allowed the measurements of the
electron temperature over 78 pixels using the line ratio forbidden O III
(4959+5007)/4363 and hence abundances of O, N, He, and Ne. A region of
high values of log N/O was found to correspond with the presence of
a cluster of Wolf-Rayet stars. Other areas of the gas complex show
the normal deficiency in log N/O for this type of object, and no
Wolf-Rayet feature is detected. There is an anticorrelation between
log N/O versus log O/H, a trend which is not clearly consistent with
any existing nucleosynthesis scenario for the origin of nitrogen in
low metallicity galaxies.
Title: The Nitrogen-to-Oxygen Ratio in the Amorphous Galaxy NGC 5253
Authors: Roy, J. -R.; Walsh, J. R.
Bibcode: 1987BAAS...19..718R
Altcode:
No abstract at ADS
Title: Imaging spectroscopy of a spiral arm of the galaxy NGC 1566.
Authors: Roy, Jean-Rene; Walsh, Jeremy R.
Bibcode: 1986MNRAS.223...39R
Altcode:
Spectra for the northwestern arm of the spiral galaxy NGC 1566 are
presented. Extinction and line-ratio maps which were calculated from
the spectra are analyzed. The behavior of various line ratios along the
length of the spiral arm, and the relationship between N II/O II, and
S II/O II forbidden line ratios and the metal-abundance index forbidden
O II + O III/H-beta are studied. It is observed that the extinction map
does not show any systematic behavior and reddening is about 2.0 + or -
0.3 mag. The data reveal that there are spatial variations of about 100
pc in the metal-abundance index forbidden O II + O III/H-beta and the
variations are due to such factors as varying the effective temperature
of the exciting stars and changing the ionization parameters.
Title: Integrated H alpha profiles of giant extragalactic H II
regions.
Authors: Arsenault, R.; Roy, J. -R.
Bibcode: 1986AJ.....92..567A
Altcode:
Integrated H-alpha profiles of 47 giant extragalactic H II regions in
26 nearby galaxies were obtained with a large-aperture Fabry-Perot
spectrometer. It is found that 66 percent of the profiles are
symmetrical and best fitted with a single Doppler component; the
remaining profiles show asymmetries and are best fitted with two or
three spectral components. More than half of the single-component
H-alpha profiles are better characterized with a de Voigt profile
than with a Gaussian profile. The H II region with complex integrated
profiles tend to have larger total widths than the H II regions with
symmetrical profiles. In two-component line profiles, the weaker
component is seen to be more often redshifted with respect to the main
component. The heliocentric radial velocities are given with other
profile parameters, and the individual profiles are presented. The
H-alpha profiles of five isolated extragalactic H II regions and of
three galaxy nuclei are also shown and briefly discussed.
Title: The H alpha Velocity Field of the Omega Nebula (M17)
Authors: Joncas, G.; Roy, J. -R.
Bibcode: 1986ApJ...307..649J
Altcode:
Using a Fabry-Perot camera, 9054 H-alpha radial velocities were measured
across the H II region M 17. The mean v(LSR) = 18.6 + or - 0.1 km/s,
which is 1.4 km/s blueshifted with respect to the mean velocity of
the associated molecular cloud M 17 SW. The dispersion of the velocity
histogram is slightly skewed to the blue. A gradient in radial velocity
is observed from west to east, with the most blueshifted velocities
appearing closest to the molecular cloud. The velocity field can be
explained as a flow of ionized gas approximatively in the plane of the
sky. There is a relation between random velocity and size, with velocity
fluctuations increasing as some power of size; the power index depends
on the sampling method of the velocity field. An interpretation of the
relation is suggested in terms of turbulence, and a brief discussion
of mechanisms for turbulent kinetic energy input is presented.
Title: The H alpha Velocity Widths of Giant H II Regions as Distance
Indicators
Authors: Roy, J. -R.; Arsenault, R.
Bibcode: 1986ApJ...302..579R
Altcode:
The mean velocity widths (MVW) of the H-alpha line profiles of the
largest giant H II regions in 10 or more galaxies are compared with
the mean diameters (MD) of the same H II regions to evaluate the
relative merits of MD and MVW as distance indicators. Diagrams of
relations M(B) versus log D and M(B) versus log W are constructed
using distance parameters from Sandage and Tammann (1981) and from de
Vaucouleurs (1979). It is shown that the mean velocity widths deduced
from integrated H-alpha line profiles correlate more strongly with
the absolute magnitudes of galaxies than the mean diameters of the
three largest H II regions; this also holds when isophotal diameters
of H II regions are used. Absolute magnitudes and distance moduli of
de Vaucouleurs give statistically more significant relationships than
the distance parameters of Sandage and Tammann.
Title: H alpha Velocity Widths in Giant Extragalactic H II Regions
Authors: Roy, J. -R.; Arsenault, R.; Joncas, G.
Bibcode: 1986ApJ...300..624R
Altcode:
Velocity dispersions have been deduced from H-alpha profiles obtained
with a Fabry-Perot interferometer spectrometer in 47 giant H II regions
observed in 16 nearby spiral and irregular Magellanic galaxies. The
velocity width W is found to be related to the size of the H II
region; the relation is significantly different from the prediction
of self-gravitation. The mean of the three largest velocity widths
of H II regions in a galaxy is closely related to the absolute blue
magnitude of the present galaxy. The shape of the relation log D-log
W is dependent on the adopted distances to the galaxies. Analysis
of detailed velocity maps of two galactic H II regions shows that
the internal relationship between the velocity width and linear size
is the same as for giant extragalactic regions. A turbulent energy
cascade is suggested as the most viable mechanism explaining both the
relationship between velocity dispersion and size and that between
velocity dispersion and the absolute magnitude of the parent galaxy.
Title: Kinematics of the HII region Sharpless 142. II. Radio continuum
and line (21 centimeter) observations.
Authors: Joncas, G.; Dewdney, P. E.; Higgs, L. A.; Roy, J. R.
Bibcode: 1985ApJ...298..596J
Altcode:
The authors present 21 cm aperture synthesis observations of the
continuum and H I line emission of a 2° field centered on the
H II region S142. The total continuum flux from S142 is 13.3 Jy,
and the peak emission measure is 15,800 cm-6pc. A simple
model of the ionized gas density distribution yields a total ionized
mass of 4000 M_sun;. Several H I emission features related to S142,
forming a partial shell around the H II region, appear to be gas which
has been dissociated by the exciting star. The total mass of H I,
≡3000 M_sun;, greatly exceeds the mass of molecular material present
(≡200 M_sun;). DH Cep, the exciting star, is contained in a young
open cluster, NGC 7380. The evolutionary history of the cluster/gas
complex is outlined.
Title: Velocity Dispersion in Giant Extragalactic H II Regions
Authors: Roy, J. R.
Bibcode: 1985BCFHT..13...15R
Altcode:
No abstract at ADS
Title: Structure and origin of velocity fluctuations in the HII
region Sharpless 142.
Authors: Roy, J. -R.; Joncas, G.
Bibcode: 1985ApJ...288..142R
Altcode:
Close to 41,000 H-alpha radial velocities have been measured across
most of the evolved H II region S142 (theta = 25 arcmin), allowing a
systematic study of velocity fluctuations. Using grids of different mesh
size to subdivide the H II region, the mean velocity dispersion, sigma,
is found to be dependent on mesh size L. A well-defined correlation
in the form of a power law sigma = L exp 0.30 is found. Because
of ambiguous interpretation of this result in terms of turbulence,
the structure function, B, which tests for velocity correlation at
all scales has also been calculated. The structure function does not
approach zero for r = 3 arcsec-90 arcsec. A brief qualitative analysis
is attempted in terms of a turbulent energy cascade in a supersonic
and compressible fluid. Kelvin-Helmholtz instabilities are suggested
for the generation and maintenance of nebular turbulence.
Title: The anomalous arms of the spiral galaxy NGC 4258.
Authors: Roy, J. R.; Arsenault, R.; Noreau, L.
Bibcode: 1985PASP...97...32R
Altcode:
The nature of the optical emission of the southern "anomalous arms" of
the spiral galaxy NGC 4258 is investigated. High-resolution spectral
scans at Hα have been obtained with a Fabry-Pérot spectrometer. No
spectral line was detected, indicating that the emission of these arms
is probably mostly continuum. A search for high optical polarization
with polarizing filters and a photon-counting camera resulted in
an upper polarization limit of 5% (1 σ), eliminating synchrotron
radiation as an important contribution to the optical emission of the
arms. It remains to be established whether the optical anomalous arms
are made of late-type stars or perhaps emitters of nonthermal continuum.
Title: Observations of the H II region, S142, in H I-line and
continuum.
Authors: Dewdney, P. E.; Higgs, L. A.; Joncas, G.; Roy, J. -R.
Bibcode: 1984JRASC..78Q.208D
Altcode:
No abstract at ADS
Title: Kinematics and dynamics of the H II region S142: the velocity
field of the ionized hydrogen.
Authors: Joncas, G.; Roy, J. -R.
Bibcode: 1984JRASC..78..209J
Altcode:
No abstract at ADS
Title: Velocity dispersion in giant extragalactic H II regions.
Authors: Arsenault, R.; Roy, J. -R.
Bibcode: 1984JRASC..78..208A
Altcode:
No abstract at ADS
Title: Kinema tics and dynamics of the HII region Sharpless
142. I. The velocity field of the ionized hydrogen.
Authors: Joncas, G.; Roy, J. -R.
Bibcode: 1984ApJ...283..640J
Altcode:
Nearly 41,000 radial velocity points across the H II region S142 have
been measured using an efficient Fabry-Perot interferometer camera and
image processing techniques. The locus of the most negative H-alpha
velocities coincides with the position of the 'hot' component of the
CO molecular cloud to the east of the nebula. The observed velocity
field is explained as a systematic expansion of the ionized gas away
from the molecular cloud and from the observer. There is a striking
match between the most negative velocities and the shape of the CO
emission contours. Some neutral material acts as a wall across the
face of the H II region, inhibiting the flow of ionized gas in the
earth's direction. The resulting flow configuration explains the radial
velocity gradient across the nebula and the fact that the mean V(LSR)
for the whole nebula is redshifted by +5 km/s with respect to the -41
km/s of the molecular cloud.
Title: A Microcomputer Controlled Fabry-Perot Spectrometer for
the Visible
Authors: Arsenault, R.; Roy, J. R.
Bibcode: 1984PASP...96..496A
Altcode:
A portable and microcomputer-controlled Fabry-Perot spectrometer used to
obtain photoelectric line profiles of galactic and extragalactic H II
regions is described. The etalon is of the piezoelectrically scanned
type and is servo-stabilized by a capacitance micrometry technique
(Hicks, Reay, and Scadden 1974). The detector is a photomultiplier with
a GaAs photocathode. Control of the scanning and data acquisition are
achieved with a HP-85 microcomputer. Spectral resolution is about 15,000
at Hα. The optical configuration of the collimator can be modified
to adapt with an f/8 or f/15 telescope aperture ratio. The maximum
field of view spectrometer on the Mount Megantic 1.60-meter telescope
is 0.8 arc minute at f/8. Examples of observations are presented and
briefly discussed.
Title: HI-Line and Continuum Observations of the Region Around S142
Authors: Dewdney, P. E.; Higgs, L. A.; Joncas, G.; Roy, J. -R.
Bibcode: 1984BAAS...16..463D
Altcode:
No abstract at ADS
Title: A Fabry-Perot camera for the study of galactic nebulae :
instrumentation and reduction of digitized interferograms.
Authors: Joncas, G.; Roy, J. -R.
Bibcode: 1984PASP...96..263J
Altcode:
The imaging mode of a portable Fabry-Perot interferometer system
is described. A focal reducer (f/8→ f/0.95) allows one to obtain
filtergrams of extended sources and, when coupled to a red Fabry-Perot
interferometer (600.0 nm to 700.0 nm), interferograms of galactic
nebulae. The detector is a photographic plate. To reduce the digitized
interferograms, a complete set of software has been developed for the
density-intensity conversion, the correction of optical distortion,
radial-velocity measurements from the interferograms, and the making of
LSR velocity maps. The algorithms are explained and some results of our
study of the H II region S142 illustrate our data-handling techniques.
Title: Book-Review - Astronomy and its History
Authors: Roy, J. R.; Swings, J. P.
Bibcode: 1984SSRv...37..402R
Altcode:
No abstract at ADS
Title: Book-Review - Astronomical Applications of Bidimensional
Photometry
Authors: Roy, Jean-René
Bibcode: 1984ApL....24..108R
Altcode: 1984ApL....24..108P
No abstract at ADS
Title: Observation of Some Exotic High Energy Interaction Without
Pion Production-Exoton
Authors: Ghosh, D.; Roy, J.; Sengupta, K.; Basu, M.; Naha, S.
Bibcode: 1983ICRC....5...35G
Altcode: 1983ICRC...18e..35G
No abstract at ADS
Title: Anomalous Interaction Mean Free Path of Secondary Particles
Emitted in C - Emulsion Interaction at 4. 5 Gev/n
Authors: Ghosh, D.; Roy, J.; Banerjee, D.; Sengupta, K.; Naha, S.
Bibcode: 1983ICRC....5..115G
Altcode: 1983ICRC...18e.115G
No abstract at ADS
Title: a Comparative Study on the Four-Momentum Transfer Between
Fireballs Produced in Hadron-Nucleus and Nucleus-Nucleus Interaction
Authors: Ghosh, D.; Roy, J.; Banerjee, D.; Sengupta, K.; Battacharjee,
A.; Guhathakurta, T.; Naha, S.; Dutta, A.; Basu, M.
Bibcode: 1983ICRC....5...31G
Altcode: 1983ICRC...18e..31G
No abstract at ADS
Title: An Investigation of Diffractive Dissocation in Multi Tev
Hadron-Hadron and Hadron-Nucleus Interaction
Authors: Ghosh, D.; Roy, J.
Bibcode: 1983ICRC....5..259G
Altcode: 1983ICRC...18e.259G
No abstract at ADS
Title: An Investigation of Non-Linear Effects in Nuclear Matter in
Heavy Ion Interaction
Authors: Ghosh, D.; Roy, J.; Banerjee, D.; Sengupta, K.; Basu, M.;
Naha, S.
Bibcode: 1983ICRC....5..242G
Altcode: 1983ICRC...18e.242G
No abstract at ADS
Title: Book-Review - Astronomy and its History
Authors: Roy, J. R.; Dyson, J. E.
Bibcode: 1983Ap&SS..91..215R
Altcode:
No abstract at ADS
Title: L'astronomie et son histoire
Authors: Roy, J. -R.
Bibcode: 1983C&T....99R..29R
Altcode:
No abstract at ADS
Title: A modular Fabry-Perot interferometer system for imagery
and spectrometry
Authors: Roy, J. -R.; Arsenault, R.; Bisson, R.; Joncas, G.
Bibcode: 1982JRASC..76..277R
Altcode:
A portable microcomputer controlled Fabry-Perot interferometer system
operating in the imaging and spectrophotometer modes has been built
to obtain radial velocity field maps and photoelectric line profiles
of galactic and extragalactic H II regions. Piezoscanning is achieved
by using capacitance micrometry to detect deviations from parallelism
and absolute spacing changes. A 183 mm focal length f/8 collimator
is used in the imaging mode, and the reimaging of the field is
accomplished using a 25 mm, f/0.95 fast lens. Design parameters in
the spectrophotometer mode include an exit diaphragm which selects
the central interference fringe of emission, and a Fabry lens which
images the primary mirror of the telescope on the GaAs photocathode
of the photomultiplier. Scanning and data acquisition are controlled
with a HP-85 microcomputer. Observations reveal that radial velocity
measurements rarely differ more than plus or minus 2 km/sec in relation
to recorded values.
Title: Dynamique des complexes H II extragalactiques: une étrange
region H II géante dans NGC 4631.
Authors: Roy, J. -R.; Arsenault, R.
Bibcode: 1982JRASC..76..325R
Altcode:
No abstract at ADS
Title: Traitement informatise des interférogrammes de Fabry-Pérot:
dynamique de la région H II S142.
Authors: Joncas, G.; Roy, J. -R.
Bibcode: 1982JRASC..76..320J
Altcode:
No abstract at ADS
Title: Un spectrophotometre interferentiel de Fabry-Pérot controlé
par micro-ordinateur.
Authors: Arsenault, R.; Roy, J. -R.; Bisson, R.
Bibcode: 1982JRASC..76R.315A
Altcode:
No abstract at ADS
Title: A Multi-Purpose Scanning Fabry-Perot Interferometer System
Authors: Roy, J. R.; Arsenault, R.; Joncas, G.
Bibcode: 1982ASSL...93...67R
Altcode: 1982rrsf.symp...67R
No abstract at ADS
Title: L'astronomie et son histoire
Authors: Roy, Jean-Rene
Bibcode: 1982ashi.book.....R
Altcode: 1982QB15.R67.......
No abstract at ADS
Title: Un système d'interférométrie à balayage pour l'imagerie
et la spectrométrie.
Authors: Roy, J. -R.; Arsenault, R.; Joncas, G.
Bibcode: 1981JRASC..75..252R
Altcode:
No abstract at ADS
Title: Study of the cluster characteristics in hadron-nucleus
interactions at ultrahigh cosmic ray energies
Authors: Ghosh, D.; Roy, J.; Naha, S.; Sengupta, K.; Basu, M.
Bibcode: 1981JPSJ...50.2799G
Altcode: 1981PSJaJ..50.2799G
In this paper we have presented an investigation of cluster
characteristics in nucleon-light nucleus and nucleon-heavy nucleus
collision in emulsion at ultrahigh cosmic ray energies (above 1 TeV)
following a model independent method proposed in a recent paper by
Shivpuri et al. It has been observed that the cluster characteristic
in both are not very different from those in case of nucleon-nucleon
collision.
Title: Comments on the Astronomical Alignments at Callanish, Lewis
Authors: Roy, J. R.
Bibcode: 1980JRASC..74....1R
Altcode:
No abstract at ADS
Title: A Comparison of the Optical and Microwave Emissions of Some
Major Solar Flares
Authors: Roy, J. -R.
Bibcode: 1979SoPh...64..143R
Altcode:
In the first part of the paper, we study the relations between the
frequency of maximum radio flux fmax and the magnetic field
strength at the photosphere Bp and between the maximum radio
flux Fmax and the field and its scale L for two differing
flares occurring above very different photospheric conditions. It
is shown that the simple relations predicted by the gyro-synchrotron
emission mechanism fmax ∼ Bp and Fmax
∼ B2L2 account for the fact that the flares
produced microwave bursts of about the same Fmax, but of
differing fmax.
Title: Cluster production in hadron-nucleus interaction at cosmic-ray
energies
Authors: Ghosh, D.; Naha, S.; Roy, J.; Bhattacharjee, A.; Roy, T.
Bibcode: 1979CaJPh..57.2026G
Altcode:
No abstract at ADS
Title: Optical and microwave emission of some major solar flares.
Authors: Roy, J. -R.
Bibcode: 1979JRASC..73..297R
Altcode:
No abstract at ADS
Title: Thick Target Models of Impulsive Chromospheric Flares
Authors: Roy, J. -Rene; Tang, Frances
Bibcode: 1978BBSOP.141....1R
Altcode:
The data from OG0-5 and OS0-7 X-ray experiments have been analyzed
to study six chromospheric flares with filament disruption associated
with slow thermal x-ray bursts. Filament activation accompanied by a
slight x-ray enhancement precedes the first evidence of Ha flare by a
few minutes. Rapid increase of the soft X-ray flux is accompanied by a
sudden brightening of the filament when viewed on-band Ha. Thereafter
the bright chromospheric strands reach their maximum brightness with
maximum X-ray flux. Any plateau or slow decay phase in the x-ray flux
is accompanied by a quieting in filament activity and even by filament
re-appearance. The height of the disrupted prominence is proportional to
the soft X-ray flux for the August 3, 1970 limb occulted event. Analysis
of the X-ray bursts on 2220 UT June 23, 1972 gives a "cool" maximum
temperature of 12.5 x 106 Kanda maximum emission measure of 40 x 10^47
cm-3. Conduction is shown to be a more efficient cooling mechanism of
the hot flare plasma than radiation. Initial heating probably occurs
in the vicinity of the filament and filament activation may visualize
some magnetic field changes which heat up the X-ray emitting plasma.
Title: Structures chromosphériques fines dans la couronne solaire
Authors: Roy, J. -R.
Bibcode: 1977JRASC..71..373R
Altcode:
Leroy (1972) predicted the existence of possible fine prominence
features to explain the presence of faint luminous chromospheric
emission in the corona. This paper draws attention to the existence of
very fine structures of the order of 200 km in width seen at H-alpha
and extending from the center of a sunspot into the corona.
Title: Alignements astronomiques du site mégalithique de Callanish,
Lewis: une critique.
Authors: Roy, J. -R.
Bibcode: 1977JRASC..71..405R
Altcode:
No abstract at ADS
Title: The north-south distribution of major solar flare events,
sunspot magnetic classes and sunspot areas (1955 1974)
Authors: Roy, J. -R.
Bibcode: 1977SoPh...52...53R
Altcode:
The north-south incidence has been studied of 31 white-light flares
observed since 1859 and of 1669 events meeting the criteria for `major
flares' of Dodson and Hedeman (1971) for the period 1955-1974. The
asymmetry in favor of the northern hemisphere increases strikingly
with the importance of the events. Similarly, magnetically complex
sunspot groups (Mt. Wilson classesβγ,γ andδ) display a more
pronounced asymmetry in favor of the north than non-complex groups for
1962-1970. Contrary to the flare asymmetry, the spottedness asymmetry
is independent of the size of sunspots.
Title: A search for microwave emission from solar X-ray bright
point flares.
Authors: Avery, L. W.; Feldman, P. A.; Gaizauskas, V.; Roy, J. -R.;
Wolfson, C. J.
Bibcode: 1977A&A....56..327A
Altcode:
An attempt was made to detect 9.4-cm radio emission from flaring
X-ray bright points with the 46-m telescope at the Algonquin Radio
Observatory. Observations from the X-ray heliometer aboard OSO-8
were combined with optical and magnetic data to substantiate possible
events. Reduction of 52 h of radio data has revealed one event which
is a candidate for radio emission from a flaring X-ray bright point.
Title: Introduction
Authors: Roy, Jean-René; Russell, Dale
Bibcode: 1977ctep.conf....5R
Altcode:
No abstract at ADS
Title: Variations of the Luminosity of the Sun and "super" Solar
Flares: Possible Causes of Extinctions
Authors: Roy, Jean-René
Bibcode: 1977ctep.conf...89R
Altcode:
No abstract at ADS
Title: Étude des champs magnétiques `sans courant' dans la couronne
solaire active
Authors: Roy, J. -R.
Bibcode: 1976JRASC..70..292R
Altcode:
The paper discusses some of the problems and typical results of
'current-free' analysis of the magnetic fields of the solar corona. Such
calculations verify the validity of photospheric magnetic field maps and
describe the magnetic lines of force in the corona above active regions.
Title: Annual Meeting of the R.A.S.C.- New Service Awards
Authors: Chilton, Kenneth E.; Roy; Belfield, Phyllis; Loehde, Franklin
Bibcode: 1976JRASC..70R.195C
Altcode:
No abstract at ADS
Title: Problems in relating the optical and X-ray emissions from a
solar flare.
Authors: Roy, J. -R.
Bibcode: 1976SoPh...48..265R
Altcode:
We evaluate the possibility that the short-lived Balmer line emission
at H9 λ3835 Å of the 1972, August 2 (1839 UT) solar flare is due to
heating of the chromosphere by bombarding electrons. We point out some
of the problems of comparing the time behavior and spatial distribution
of simultaneous hard and soft X-ray emissions. It is concluded that
the present data do not justify the attribution of the short-lived
optical emission to the presumed hard X-ray producing electrons.
Title: Observations of a surge prominence as a continuum event.
Authors: Roy, J. -R.
Bibcode: 1976SoPh...48..149R
Altcode:
Observations of a surge prominence event on 31 May 1971 are
discussed. The continuum emission observed during the upward
acceleration of the surge is attributed to the scattering of
photospheric radiation by free electrons. The observed scattered
light intensity amounts to a few times 10−5 that
of the central disk intensity leading to a column density of
neL≈1020 cm−2. The actual electron
density when taking into account the presence of inhomogeneities is
ne≈1012 cm−3. The dynamic and
morphological behaviour of the surge is considered.
Title: Slow X-Ray Bursts and Flares with Filament Disruption
Authors: Roy, J. -R.; Tang, F.
Bibcode: 1975SoPh...42..425R
Altcode:
The data from OGO-5 and OSO-7 X-ray experiments have been compared with
optical data from six chromospheric flares with filament disruption
associated with slow thermal X-ray bursts. Filament activation
accompanied by a slight X-ray enhancement precedes the first evidence
of Hα flare by a few minutes. Rapid increase of the soft X-ray flux
accompanies the phase of fastest expansion of the filament. Plateau
or slow decay phases in the X-ray flux are associated with slowing
and termination of filament expansion. The soft X-ray flux increases
as F∼(A + Bh) h, where h is the height of the disrupted prominence
at any given time and A and B are constants. We suggest that the soft
X-ray emission originates from a growing shell of roughly constant
thickness of high-temperature plasma due to the compression of the
coronal gas by the expanding prominence.
Title: Slow X-ray bursts and chromospheric flares with filament
disruption.
Authors: Roy, J. R.; Tang, F.
Bibcode: 1975sxbc.book.....R
Altcode: 1975STIN...7517281R
The data from OGO-5 and OSO-7 X-ray experiments have been analyzed to
study six chromospheric flares with filament disruption associated
with slow thermal X-ray bursts. Filament activation accompanied by
a slight X-ray enhancement precedes the first evidence of H alpha
flare by a few minutes. Rapid increase of the soft X-ray flux is
accompanied by a sudden brightening of the filament when viewed on-band
H alpha. Thereafter the bright chromospheric strands reach their maximum
brightness with maximum X-ray flux. Any plateau or slow decay phase in
the X-ray flux is accompanied by a quieting in filament activity and
even by filament re-appearance. The height of the disrupted prominence
is proportional to the soft X-ray flux for the August 3, 1970 limb
occulted event.
Title: X-Ray Bursts from Solar Flares behind the Limb
Authors: Roy, J. -R.; Datlowe, D. W.
Bibcode: 1975SoPh...40..165R
Altcode:
From the UCSD OSO-7 X-ray experiment data, we have identified 54
X-ray bursts with 5.1-6.6 keV flux greater than 103 photon
cm−2 keV−1 which were not accompanied
by visible Hα flare on the solar disk. By studying OSO-5 X-ray
spectroheliograms, Hα activity at the limb and the emergence and
disappearance of sunspot groups at the limb, we found 17 active centers
as likely seats of the X-ray bursts beyond the limb. We present the
analysis of 37 X-ray bursts and their physical parameters. We compare
our results with those published by Datlowe et al. (1974a, b) for
disk events.
Title: X-ray bursts from solar flares behind the limb.
Authors: Roy, J. R.; Datlowe, D. W.
Bibcode: 1975xbfs.book.....R
Altcode: 1975STIN...7517278R
X-ray bursts are identified from the UCSD OSO-7 X-ray experiment
data. X-ray spectroheliograms of OSO-5, H alpha activity at the limb,
and the emergence and disappearance of sunspot groups at the limb
were studied and 17 active centers were found as likely seats of
the X-ray bursts beyond the limb. The analysis of 37 X-ray bursts
and their physical parameters is presented. Results show that (1)
the distributions of maximum temperature, maximum emission measure,
and characteristic cooling time of the over-the-limb events do not
significantly differ from those of disk events; (2) that radiation
is the dominant cooling mechanism for the hot flare plasma; and (3)
that the scale height for X-ray emission in the 5-10 keV range is
large. Observations show that the fraction of soft X-ray bursts which
have a nonthermal component is the same on and off of the disk. Hard
X-ray emission over extended regions is indicated.
Title: The late June 1972 CINOF flares
Authors: Rust, D. M.; Roy, J. R.
Bibcode: 1974erp..rept.....R
Altcode:
This report is the result of an analysis of observations obtained during
the campaign for integrated observations of solar flares. The aim
was to obtain a more complete set of optical, radio, X-ray, EUV, and
particle observations of a normal solar flare than has been available
from earlier, uncoordinated efforts. Flares observed in the McMath
regions are discussed, with emphasis on optical and X-ray observations.
Title: Chromospheric activity associated with moving photospheric
magnetic fields
Authors: Roy, J. -René; Michalitsanos, A. G.
Bibcode: 1974SoPh...35...47R
Altcode:
With the aid of Hα and Ca II K filtergrams and magnetograms of region
McMath 12417 on 3, 4 and 5 July 1973, we have followed the evolution of
a moving rim of positive magnetic flux 50″ long in an area dominated
by negative flux. Chromospheric activity in the form of brightenings
and small surges was associated with this moving flux; a concentration
of activity is observed at the locations where magnetic fields of
opposite sign meet together. The weakening of the Ca II K emission
along the edges of colliding opposite fields supports evidence from
magnetograms that the photospheric magnetic field at that location
has decreased strikingly over a period of six hours.
Title: Chromospheric Activity Associated With Moving Photospheric
Magnetic Field
Authors: Roy, J. R.; Michalitsianos, A. G.
Bibcode: 1974BAAS....6S.293R
Altcode:
No abstract at ADS
Title: The Dynamics of Solar Surges
Authors: Roy, J. -René
Bibcode: 1973SoPh...32..139R
Altcode:
Curves of velocity as a function of height have been determined from
time sequences of on- and off-band Hα filtergrams of four surges. The
surges behave as predicted by the melon-seed mechanism. However, in the
outward-moving material the deceleration taking place after the maximum
velocity has been reached, is stronger than if gravity alone is acting
in three of four cases; during the return phase, the acceleration toward
the solar surface is less than free-fall in two of three cases. The
braking force, opposing the motion, is proportional to the velocity
of the surge material. Non-force-free effects in the magnetic field
supporting the surge provide a reasonable explanation for the braking.
Title: Some Statistical Properties of Ellerman Bombs
Authors: Roy, J. -René; Leparskas, H.
Bibcode: 1973SoPh...30..449R
Altcode:
One hundred seventy-eight Ellerman bombs were identified and studied
with on- and off-band Hα filtergrams of two active centers, one near
disk center and the other near the east limb. The photographs, taken
through a 1/4 Å bandpass filter, occasionally attained resolution as
fine as 0.3″. The mean duration of bombs at Hα-2 Å was about 13 min
near disk center and 11 min near the limb; these times increase slightly
when we observe closer to the core of Hα. Eighty-six percent of the
bombs in the near-limb region and 56% in the disk-center region were
seen to be accompanied by ejections of dark material; the ejections
were 3-30″ long. The ejection length appears to be proportional to
the bomb size times the bomb lifetime.
Title: The Magnetic Properties of Solar Surges
Authors: Roy, J. René
Bibcode: 1973SoPh...28...95R
Altcode:
High resolution on- and off-band Hα filtergrams of disk solar surges
obtained with the Vacuum Tower Telescope of the Sacramento Peak
Observatory have been compared to magnetic data. Surges constitute
clusters of very fine dark (sometimes bright) filaments where each
thread connects to an Ellerman bomb brightening. If the magnetic
map reveals the existence of a satellite polarity as defined by Rust
(1968), the bomb(s) lies over it.
Title: Solar Surges: Magnetic Properties, Dynamics and Structure.
Authors: Roy, Jean-Rene
Bibcode: 1973PhDT.........7R
Altcode:
No abstract at ADS
Title: Solar surges: Magnetic properties, dynamics and structure
Authors: Roy, Jean-René
Bibcode: 1973PhDT.......106R
Altcode:
No abstract at ADS
Title: The Magnetic Configuration of the November 18, 1968 Loop
Prominence System
Authors: Roy, J. -René
Bibcode: 1972SoPh...26..418R
Altcode:
Computed current-free magnetic fields are compared to the loop
prominence associated with the west limb proton flare of 18 November
1968. Successive sets of fitting fieldlines closely resemble the loop
prominence system throughout its growth and lifetime. The successive
position bases of the fieldlines reproduce the drift rate of spreading
two-ribbon flares.
Title: The magnetic field configuration of the solar corona after
a proton flare.
Authors: Roy, J. -R.
Bibcode: 1972JRASC..66..220R
Altcode:
No abstract at ADS
Title: Models for the Envelopes of be Stars. III. Pole-On Stars
Authors: Marlborough, J. M.; Roy, J. Rene
Bibcode: 1971ApJ...169..327M
Altcode:
Ha line profiles are presented for model envelopes for which the
observer's line of sight is parallel to the rotation axis of the
star. A comparison is made of these line profiles with the predicted
Ha line profiles for the same model envelope when the observer's line
of sight is perpendicular to the rotation axis.
Title: Coronal Magnetic Fields above Active Regions
Authors: Rust, D. M.; Roy, J. -R.
Bibcode: 1971IAUS...43..569R
Altcode:
No abstract at ADS
Title: Supersonic Stellar Winds in Early-Type Stars
Authors: Marlborough, J. M.; Roy, J. René
Bibcode: 1970ApJ...160..221M
Altcode:
The effect on stellar winds of the mechanical force due to radiation
is considered in general. If the flow velocity is initially subsonic
in or near the star, it is shown that a supersonic stellar wind cannot
arise as a result of the mechanical force due to radiation balancing
or exceeding the gravitational force.