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Author name code: goodman
ADS astronomy entries on 2022-09-14
author:"Goodman, Michael L."
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Title: Review of Particle Physics
Authors: Particle Data Group; Zyla, P. A.; Barnett, R. M.; Beringer,
J.; Dahl, O.; Dwyer, D. A.; Groom, D. E.; Lin, C. -J.; Lugovsky,
K. S.; Pianori, E.; Robinson, D. J.; Wohl, C. G.; Yao, W. -M.;
Agashe, K.; Aielli, G.; Allanach, B. C.; Amsler, C.; Antonelli, M.;
Aschenauer, E. C.; Asner, D. M.; Baer, H.; Banerjee, Sw; Baudis, L.;
Bauer, C. W.; Beatty, J. J.; Belousov, V. I.; Bethke, S.; Bettini,
A.; Biebel, O.; Black, K. M.; Blucher, E.; Buchmuller, O.; Burkert,
V.; Bychkov, M. A.; Cahn, R. N.; Carena, M.; Ceccucci, A.; Cerri,
A.; Chakraborty, D.; Chivukula, R. Sekhar; Cowan, G.; D'Ambrosio, G.;
Damour, T.; de Florian, D.; de Gouvêa, A.; DeGrand, T.; de Jong, P.;
Dissertori, G.; Dobrescu, B. A.; D'Onofrio, M.; Doser, M.; Drees, M.;
Dreiner, H. K.; Eerola, P.; Egede, U.; Eidelman, S.; Ellis, J.; Erler,
J.; Ezhela, V. V.; Fetscher, W.; Fields, B. D.; Foster, B.; Freitas,
A.; Gallagher, H.; Garren, L.; Gerber, H. -J.; Gerbier, G.; Gershon,
T.; Gershtein, Y.; Gherghetta, T.; Godizov, A. A.; Gonzalez-Garcia,
M. C.; Goodman, M.; Grab, C.; Gritsan, A. V.; Grojean, C.; Grünewald,
M.; Gurtu, A.; Gutsche, T.; Haber, H. E.; Hanhart, C.; Hashimoto, S.;
Hayato, Y.; Hebecker, A.; Heinemeyer, S.; Heltsley, B.; Hernández-Rey,
J. J.; Hikasa, K.; Hisano, J.; Höcker, A.; Holder, J.; Holtkamp, A.;
Huston, J.; Hyodo, T.; Johnson, K. F.; Kado, M.; Karliner, M.; Katz,
U. F.; Kenzie, M.; Khoze, V. A.; Klein, S. R.; Klempt, E.; Kowalewski,
R. V.; Krauss, F.; Kreps, M.; Krusche, B.; Kwon, Y.; Lahav, O.; Laiho,
J.; Lellouch, L. P.; Lesgourgues, J.; Liddle, A. R.; Ligeti, Z.;
Lippmann, C.; Liss, T. M.; Littenberg, L.; Lourengo, C.; Lugovsky,
S. B.; Lusiani, A.; Makida, Y.; Maltoni, F.; Mannel, T.; Manohar,
A. V.; Marciano, W. J.; Masoni, A.; Matthews, J.; Meißner, U. -G.;
Mikhasenko, M.; Miller, D. J.; Milstead, D.; Mitchell, R. E.; Mönig,
K.; Molaro, P.; Moortgat, F.; Moskovic, M.; Nakamura, K.; Narain, M.;
Nason, P.; Navas, S.; Neubert, M.; Nevski, P.; Nir, Y.; Olive, K. A.;
Patrignani, C.; Peacock, J. A.; Petcov, S. T.; Petrov, V. A.; Pich,
A.; Piepke, A.; Pomarol, A.; Profumo, S.; Quadt, A.; Rabbertz, K.;
Rademacker, J.; Raffelt, G.; Ramani, H.; Ramsey-Musolf, M.; Ratcliff,
B. N.; Richardson, P.; Ringwald, A.; Roesler, S.; Rolli, S.; Romaniouk,
A.; Rosenberg, L. J.; Rosner, J. L.; Rybka, G.; Ryskin, M.; Ryutin,
R. A.; Sakai, Y.; Salam, G. P.; Sarkar, S.; Sauli, F.; Schneider, O.;
Scholberg, K.; Schwartz, A. J.; Schwiening, J.; Scott, D.; Sharma,
V.; Sharpe, S. R.; Shutt, T.; Silari, M.; Sjöstrand, T.; Skands,
P.; Skwarnicki, T.; Smoot, G. F.; Soffer, A.; Sozzi, M. S.; Spanier,
S.; Spiering, C.; Stahl, A.; Stone, S. L.; Sumino, Y.; Sumiyoshi, T.;
Syphers, M. J.; Takahashi, F.; Tanabashi, M.; Tanaka, J.; Taševský,
M.; Terashi, K.; Terning, J.; Thoma, U.; Thorne, R. S.; Tiator, L.;
Titov, M.; Tkachenko, N. P.; Tovey, D. R.; Trabelsi, K.; Urquijo, P.;
Valencia, G.; Van de Water, R.; Varelas, N.; Venanzoni, G.; Verde,
L.; Vincter, M. G.; Vogel, P.; Vogelsang, W.; Vogt, A.; Vorobyev,
V.; Wakely, S. P.; Walkowiak, W.; Walter, C. W.; Wands, D.; Wascko,
M. O.; Weinberg, D. H.; Weinberg, E. J.; White, M.; Wiencke, L. R.;
Willocq, S.; Woody, C. L.; Workman, R. L.; Yokoyama, M.; Yoshida,
R.; Zanderighi, G.; Zeller, G. P.; Zenin, O. V.; Zhu, R. -Y.; Zhu,
S. -L.; Zimmermann, F.; Anderson, J.; Basaglia, T.; Lugovsky, V. S.;
Schaffner, P.; Zheng, W.
2020PTEP.2020h3C01P Altcode:
The Review summarizes much of particle physics and cosmology. Using data
from previous editions, plus 3,324 new measurements from 878 papers,
we list, evaluate, and average measured properties of gauge bosons
and the recently discovered Higgs boson, leptons, quarks, mesons,
and baryons. We summarize searches for hypothetical particles such
as supersymmetric particles, heavy bosons, axions, dark photons,
etc. Particle properties and search limits are listed in Summary
Tables. We give numerous tables, figures, formulae, and reviews of
topics such as Higgs Boson Physics, Supersymmetry, Grand Unified
Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology,
Particle Detectors, Colliders, Probability and Statistics. Among
the 120 reviews are many that are new or heavily revised, including
a new review on High Energy Soft QCD and Diffraction and one on the
Determination of CKM Angles from B Hadrons.
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Title: A new approach to solar flare prediction
Authors: Goodman, Michael L.; Kwan, Chiman; Ayhan, Bulent; Shang,
Eric L.
2020FrPhy..1534601G Altcode: 2020arXiv200301823G
All three components of the current density are required to compute
the heating rate due to free magnetic energy dissipation. Here we
present a first test of a new model developed to determine if the
times of increases in the resistive heating rate in active region
(AR) photospheres are correlated with the subsequent occurrence
of M and X flares in the corona. A data driven, 3D, non-force-free
magnetohydrodynamic model restricted to the near-photospheric region
is used to compute time series of the complete current density and the
resistive heating rate per unit volume [Q(t)] in each pixel in neutral
line regions (NLRs) of 14 ARs. The model is driven by time series
of the magnetic field B measured by the Helioseismic & Magnetic
Imager on the Solar Dynamics Observatory (SDO) satellite. Spurious
Doppler periods due to SDO orbital motion are filtered out of the
time series for B in every AR pixel. For each AR, the cumulative
distribution function (CDF) of the values of the NLR area integral
Q<SUB>i</SUB>(t) of Q(t) is found to be a scale invariant power law
distribution essentially identical to the observed CDF for the total
energy released in coronal flares. This suggests that coronal flares
and the photospheric Q<SUB>i</SUB> are correlated, and powered by the
same process. The model predicts spikes in Q<SUB>i</SUB> with values
orders of magnitude above background values. These spikes are driven
by spikes in the non-force free component of the current density. The
times of these spikes are plausibly correlated with times of subsequent
M or X flares a few hours to a few days later. The spikes occur on
granulation scales, and may be signatures of heating in horizontal
current sheets. It is also found that the times of relatively large
values of the rate of change of the NLR unsigned magnetic flux are
also plausibly correlated with the times of subsequent M and X flares,
and spikes in Q<SUB>i</SUB>.
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Title: Review of Particle Physics<SUP>*</SUP>
Authors: Tanabashi, M.; Hagiwara, K.; Hikasa, K.; Nakamura, K.; Sumino,
Y.; Takahashi, F.; Tanaka, J.; Agashe, K.; Aielli, G.; Amsler, C.;
Antonelli, M.; Asner, D. M.; Baer, H.; Banerjee, Sw.; Barnett, R. M.;
Basaglia, T.; Bauer, C. W.; Beatty, J. J.; Belousov, V. I.; Beringer,
J.; Bethke, S.; Bettini, A.; Bichsel, H.; Biebel, O.; Black, K. M.;
Blucher, E.; Buchmuller, O.; Burkert, V.; Bychkov, M. A.; Cahn, R. N.;
Carena, M.; Ceccucci, A.; Cerri, A.; Chakraborty, D.; Chen, M. -C.;
Chivukula, R. S.; Cowan, G.; Dahl, O.; D'Ambrosio, G.; Damour, T.;
de Florian, D.; de Gouvêa, A.; DeGrand, T.; de Jong, P.; Dissertori,
G.; Dobrescu, B. A.; D'Onofrio, M.; Doser, M.; Drees, M.; Dreiner,
H. K.; Dwyer, D. A.; Eerola, P.; Eidelman, S.; Ellis, J.; Erler, J.;
Ezhela, V. V.; Fetscher, W.; Fields, B. D.; Firestone, R.; Foster, B.;
Freitas, A.; Gallagher, H.; Garren, L.; Gerber, H. -J.; Gerbier, G.;
Gershon, T.; Gershtein, Y.; Gherghetta, T.; Godizov, A. A.; Goodman,
M.; Grab, C.; Gritsan, A. V.; Grojean, C.; Groom, D. E.; Grünewald,
M.; Gurtu, A.; Gutsche, T.; Haber, H. E.; Hanhart, C.; Hashimoto, S.;
Hayato, Y.; Hayes, K. G.; Hebecker, A.; Heinemeyer, S.; Heltsley, B.;
Hernández-Rey, J. J.; Hisano, J.; Höcker, A.; Holder, J.; Holtkamp,
A.; Hyodo, T.; Irwin, K. D.; Johnson, K. F.; Kado, M.; Karliner, M.;
Katz, U. F.; Klein, S. R.; Klempt, E.; Kowalewski, R. V.; Krauss, F.;
Kreps, M.; Krusche, B.; Kuyanov, Yu. V.; Kwon, Y.; Lahav, O.; Laiho,
J.; Lesgourgues, J.; Liddle, A.; Ligeti, Z.; Lin, C. -J.; Lippmann, C.;
Liss, T. M.; Littenberg, L.; Lugovsky, K. S.; Lugovsky, S. B.; Lusiani,
A.; Makida, Y.; Maltoni, F.; Mannel, T.; Manohar, A. V.; Marciano,
W. J.; Martin, A. D.; Masoni, A.; Matthews, J.; Meißner, U. -G.;
Milstead, D.; Mitchell, R. E.; Mönig, K.; Molaro, P.; Moortgat, F.;
Moskovic, M.; Murayama, H.; Narain, M.; Nason, P.; Navas, S.; Neubert,
M.; Nevski, P.; Nir, Y.; Olive, K. A.; Pagan Griso, S.; Parsons, J.;
Patrignani, C.; Peacock, J. A.; Pennington, M.; Petcov, S. T.; Petrov,
V. A.; Pianori, E.; Piepke, A.; Pomarol, A.; Quadt, A.; Rademacker, J.;
Raffelt, G.; Ratcliff, B. N.; Richardson, P.; Ringwald, A.; Roesler,
S.; Rolli, S.; Romaniouk, A.; Rosenberg, L. J.; Rosner, J. L.; Rybka,
G.; Ryutin, R. A.; Sachrajda, C. T.; Sakai, Y.; Salam, G. P.; Sarkar,
S.; Sauli, F.; Schneider, O.; Scholberg, K.; Schwartz, A. J.; Scott,
D.; Sharma, V.; Sharpe, S. R.; Shutt, T.; Silari, M.; Sjöstrand,
T.; Skands, P.; Skwarnicki, T.; Smith, J. G.; Smoot, G. F.; Spanier,
S.; Spieler, H.; Spiering, C.; Stahl, A.; Stone, S. L.; Sumiyoshi,
T.; Syphers, M. J.; Terashi, K.; Terning, J.; Thoma, U.; Thorne,
R. S.; Tiator, L.; Titov, M.; Tkachenko, N. P.; Törnqvist, N. A.;
Tovey, D. R.; Valencia, G.; Van de Water, R.; Varelas, N.; Venanzoni,
G.; Verde, L.; Vincter, M. G.; Vogel, P.; Vogt, A.; Wakely, S. P.;
Walkowiak, W.; Walter, C. W.; Wands, D.; Ward, D. R.; Wascko, M. O.;
Weiglein, G.; Weinberg, D. H.; Weinberg, E. J.; White, M.; Wiencke,
L. R.; Willocq, S.; Wohl, C. G.; Womersley, J.; Woody, C. L.; Workman,
R. L.; Yao, W. -M.; Zeller, G. P.; Zenin, O. V.; Zhu, R. -Y.; Zhu,
S. -L.; Zimmermann, F.; Zyla, P. A.; Anderson, J.; Fuller, L.;
Lugovsky, V. S.; Schaffner, P.; Particle Data Group
2018PhRvD..98c0001T Altcode:
The Review summarizes much of particle physics and cosmology. Using data
from previous editions, plus 2,873 new measurements from 758 papers,
we list, evaluate, and average measured properties of gauge bosons
and the recently discovered Higgs boson, leptons, quarks, mesons,
and baryons. We summarize searches for hypothetical particles such
as supersymmetric particles, heavy bosons, axions, dark photons,
etc. Particle properties and search limits are listed in Summary
Tables. We give numerous tables, figures, formulae, and reviews
of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified
Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle
Detectors, Colliders, Probability and Statistics. Among the 118 reviews
are many that are new or heavily revised, including a new review on
Neutrinos in Cosmology. <P />Starting with this edition, the Review
is divided into two volumes. Volume 1 includes the Summary Tables and
all review articles. Volume 2 consists of the Particle Listings. Review
articles that were previously part of the Listings are now included in
volume 1. <P />The complete Review (both volumes) is published online
on the website of the Particle Data Group (http://pdg.lbl.gov) and in
a journal. Volume 1 is available in print as the PDG Book. A Particle
Physics Booklet with the Summary Tables and essential tables, figures,
and equations from selected review articles is also available. <P />The
2018 edition of the Review of Particle Physics should be cited as:
M. Tanabashi et al. (Particle Data Group), Phys. Rev. D 98, 030001
(2018).
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Title: Cosmic-muon characterization and annual modulation measurement
with Double Chooz detectors
Authors: Abrahão, T.; Almazan, H.; dos Anjos, J. C.; Appel, S.;
Baussan, E.; Bekman, I.; Bezerra, T. J. C.; Bezrukov, L.; Blucher,
E.; Brugière, T.; Buck, C.; Busenitz, J.; Cabrera, A.; Camilleri,
L.; Carr, R.; Cerrada, M.; Chauveau, E.; Chimenti, P.; Corpace,
O.; Crespo-Anadón, J. I.; Dawson, J. V.; Dhooghe, J.; Djurcic, Z.;
Dracos, M.; Etenko, A.; Fallot, M.; Franco, D.; Franke, M.; Furuta,
H.; Gil-Botella, I.; Giot, L.; Givaudan, A.; Gögger-Neff, M.; Gómez,
H.; Gonzalez, L. F. G.; Goodman, M.; Hara, T.; Haser, J.; Hellwig,
D.; Hourlier, A.; Ishitsuka, M.; Jochum, J.; Jollet, C.; Kale, K.;
Kampmann, P.; Kaneda, M.; Kaplan, D. M.; Kawasaki, T.; Kemp, E.; de
Kerret, H.; Kryn, D.; Kuze, M.; Lachenmaier, T.; Lane, C.; Laserre, T.;
Lastoria, C.; Lhuillier, D.; Lima, H.; Lindner, M.; López-Castaño,
J. M.; LoSecco, J. M.; Lubsandorzhiev, B.; Maeda, J.; Mariani, C.;
Maricic, J.; Matsubara, T.; Mention, G.; Meregaglia, A.; Miletic, T.;
Minotti, A.; Nagasaka, Y.; Navas-Nicolás, D.; Novella, P.; Oberauer,
L.; Obolensky, M.; Onillon, A.; Oralbaev, A.; Palomares, C.; Pepe,
I.; Pronost, G.; Reinhold, B.; Rybolt, B.; Sakamoto, Y.; Santorelli,
R.; Schönert, S.; Schoppmann, S.; Sharankova, R.; Sibille, V.; Sinev,
V.; Skorokhvatov, M.; Soiron, M.; Soldin, P.; Stahl, A.; Stancu, I.;
Stokes, L. F. F.; Strait, M.; Suekane, F.; Sukhotin, S.; Sumiyoshi,
T.; Sun, Y.; Svoboda, B.; Tonazzo, A.; Veyssiere, C.; Vivier, M.;
Wagner, S.; Wiebusch, C.; Wurm, M.; Yang, G.; Yermia, F.; Zimmer, V.
2017JCAP...02..017A Altcode: 2016arXiv161107845A
A study on cosmic muons has been performed for the two identical
near and far neutrino detectors of the Double Chooz experiment,
placed at ~120 and ~300 m.w.e. underground respectively,
including the corresponding simulations using the MUSIC simulation
package. This characterization has allowed us to measure the muon
flux reaching both detectors to be (3.64 ± 0.04) × 10<SUP>-4</SUP>
cm<SUP>-2</SUP>s<SUP>-1</SUP> for the near detector and (7.00 ± 0.05)
× 10<SUP>-5</SUP> cm<SUP>-2</SUP>s<SUP>-1</SUP> for the far one. The
seasonal modulation of the signal has also been studied observing a
positive correlation with the atmospheric temperature, leading to an
effective temperature coefficient of α<SUB>T</SUB> = 0.212 ± 0.024
and 0.355 ± 0.019 for the near and far detectors respectively. These
measurements, in good agreement with expectations based on theoretical
models, represent one of the first measurements of this coefficient
in shallow depth installations.
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Title: Seasonal Variation of Multiple-Muon Events in MINOS and NOvA
Authors: Habig, A.; Goodman, M.; Schreiner, P.; Tognini, S.; Gomes,
R.; Minos Collaboration; Nova Collaboration
2017ICRC...35..200H Altcode: 2017PoS...301..200H
No abstract at ADS
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Title: Neutrino Oscillations in the NOvA experiment
Authors: Habig, A.; Goodman, M.; NOvA Collaboration
2017ICRC...35.1023H Altcode: 2017PoS...301.1023H
No abstract at ADS
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Title: Photospheric Current Spikes And Their Possible Association
With Flares - Results from an HMI Data Driven Model
Authors: Goodman, M. L.; Kwan, C.; Ayhan, B.; Eric, S. L.
2016AGUFMSH31B2562G Altcode:
A data driven, near photospheric magnetohydrodynamic model predicts
spikes in the horizontal current density, and associated resistive
heating rate. The spikes appear as increases by orders of magnitude
above background values in neutral line regions (NLRs) of active regions
(ARs). The largest spikes typically occur a few hours to a few days
prior to M or X flares. The spikes correspond to large vertical
derivatives of the horizontal magnetic field. The model takes as
input the photospheric magnetic field observed by the Helioseismic
& Magnetic Imager (HMI) on the Solar Dynamics Observatory
(SDO) satellite. This 2.5 D field is used to determine an analytic
expression for a 3 D magnetic field, from which the current density,
vector potential, and electric field are computed in every AR pixel
for 14 ARs. The field is not assumed to be force-free. The spurious 6,
12, and 24 hour Doppler periods due to SDO orbital motion are filtered
out of the time series of the HMI magnetic field for each pixel. The
subset of spikes analyzed at the pixel level are found to occur on
HMI and granulation scales of 1 arcsec and 12 minutes. Spikes are
found in ARs with and without M or X flares, and outside as well as
inside NLRs, but the largest spikes are localized in the NLRs of ARs
with M or X flares. The energy to drive the heating associated with
the largest current spikes comes from bulk flow kinetic energy, not
the electromagnetic field, and the current density is highly non-force
free. The results suggest that, in combination with the model, HMI is
revealing strong, convection driven, non-force free heating events on
granulation scales, and it is plausible these events are correlated
with subsequent M or X flares. More and longer time series need to be
analyzed to determine if such a correlation exists.
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Title: Basic Properties of Plasma-Neutral Coupling in the Solar
Atmosphere
Authors: Goodman, Michael
2015TESS....140001G Altcode:
Plasma-neutral coupling (PNC) in the solar atmosphere concerns the
effects of collisions between charged and neutral species’. It
is most important in the chromosphere, which is the weakly ionized,
strongly magnetized region between the weakly ionized, weakly magnetized
photosphere and the strongly ionized, strongly magnetized corona. The
charged species’ are mainly electrons, protons, and singly charged
heavy ions. The neutral species’ are mainly hydrogen and helium. The
resistivity due to PNC can be several orders of magnitude larger than
the Spitzer resistivity. This enhanced resistivity is confined to the
chromosphere, and provides a highly efficient dissipation mechanism
unique to the chromosphere. PNC may play an important role in many
processes such as heating and acceleration of plasma; wave generation,
propagation, and dissipation; magnetic reconnection; maintaining the
near force-free state of the corona; and limiting mass flux into the
corona. It might play a major role in chromospheric heating, and be
responsible for the existence of the chromosphere as a relatively thin
layer of plasma that emits a net radiative flux 10-100 times greater
than that of the overlying corona. The required heating rate might
be generated by Pedersen current dissipation triggered by the rapid
increase of magnetization with height in the lower chromosphere,
where most of the net radiative flux is emitted. Relatively cool
regions of the chromosphere might be regions of minimal Pedersen
current dissipation due to smaller magnetic field strength or
perpendicular current density. This talk will discuss PNC from an MHD
point of view, and focus on the basic parameters that determine its
effectiveness. These parameters are ionization fraction, magnetization,
and the electric field that drives current perpendicular to the
magnetic field. By influencing this current and the electric field
that drives it, PNC directly influences the rate at which energy is
exchanged between the electromagnetic field and particles. In this
way, PNC can have a strong influence on the energetics of a process
that involves the conversion of magnetic energy into particle energy,
which subsequently appears as radiation, waves, bulk flow, and heating.
---------------------------------------------------------
Title: Acceleration of Type 2 Spicules in the Solar
Chromosphere. II. Viscous Braking and Upper Bounds on Coronal
Energy Input
Authors: Goodman, Michael L.
2014ApJ...785...87G Altcode: 2014arXiv1403.2694G
A magnetohydrodynamic model is used to determine conditions under which
the Lorentz force accelerates plasma to type 2 spicule speeds in the
chromosphere. The model generalizes a previous model to include a more
realistic pre-spicule state, and the vertical viscous force. Two cases
of acceleration under upper chromospheric conditions are considered. The
magnetic field strength for these cases is <=12.5 and 25 G. Plasma is
accelerated to terminal vertical speeds of 66 and 78 km s<SUP>-1</SUP>
in 100 s, compared with 124 and 397 km s<SUP>-1</SUP> for the
case of zero viscosity. The flows are localized within horizontal
diameters ~80 and 50 km. The total thermal energy generated by viscous
dissipation is ~10 times larger than that due to Joule dissipation,
but the magnitude of the total cooling due to rarefaction is >~
this energy. Compressive heating dominates during the early phase of
acceleration. The maximum energy injected into the corona by type 2
spicules, defined as the energy flux in the upper chromosphere, may
largely balance total coronal energy losses in quiet regions, possibly
also in coronal holes, but not in active regions. It is proposed that
magnetic flux emergence in intergranular regions drives type 2 spicules.
---------------------------------------------------------
Title: Acceleration of Type II Spicules in the Solar Chromosphere
Authors: Goodman, M. L.
2012AGUFMSH33D2258G Altcode:
A 2.5 D, time dependent magnetohydrodynamic model is used to test the
proposition that observed type II spicule velocities can be generated
by a Lorentz force under chromospheric conditions, and that maximum
vertical flow speeds can be comparable to slow solar wind speeds
∼ 200-400 km/sec. It is found that current densities localized on
observed space and time scales of type II spicules, and that generate
maximum magnetic field strengths ≤ 50 G can generate a Lorentz force
that accelerates plasma to terminal velocities similar to those of
type II spicules. The maximum vertical flow speeds are ∼ 150-460
km-sec<SUP>-1</SUP>, and horizontally localized within ∼ 2.5-10 km
from the vertical axis of the spicule, suggesting that significant
solar wind acceleration occurs in type II spicules on sub-resolution,
horizontal spatial scales. Vertical flow speeds with Mach numbers
> ∼ 5 extend over horizontal regions with diameters ∼ 25-50
km. Horizontal speeds are ∼ 20 times smaller than maximum vertical
speeds. The increase in the mechanical and thermal energy of the plasma
during the acceleration process is 2-3 × 10<SUP>22</SUP> ergs, which
is ∼ 5 times smaller than nanoflare energies. The radial component of
the Lorentz force compresses the plasma during the acceleration process
by factors as large as ∼ 100. The Joule heating flux generated during
this process is essentially due to proton Pedersen current dissipation,
and can be ∼ 0.1 - 3.7 times the heating flux of ∼ 10<SUP>6</SUP>
ergs-cm<SUP>-2</SUP>-s<SUP>-1</SUP> associated with middle-upper
chromospheric emission. The maximum heating rate and vertical flow speed
are respectively reached ∼ 23 s and 100 s after acceleration begins,
indicating that most heating occurs well before terminal velocity
is reached. About 84-94% of the magnetic energy that accelerates and
heats the spicules is converted into bulk flow kinetic energy.
---------------------------------------------------------
Title: Acceleration of Type II Spicules in the Solar Chromosphere
Authors: Goodman, Michael L.
2012ApJ...757..188G Altcode:
A 2.5D, time-dependent magnetohydrodynamic model is used to test the
proposition that observed type II spicule velocities can be generated
by a Lorentz force under chromospheric conditions. It is found that
current densities localized on observed space and time scales of type
II spicules and that generate maximum magnetic field strengths <=50
G can generate a Lorentz force that accelerates plasma to terminal
velocities similar to those of type II spicules. Maximum vertical flow
speeds are ~150-460 km s<SUP>-1</SUP>, horizontally localized within
~2.5-10 km from the vertical axis of the spicule, and comparable
to slow solar wind speeds, suggesting that significant solar wind
acceleration occurs in type II spicules. Horizontal speeds are ~20
times smaller than vertical speeds. Terminal velocity is reached ~100 s
after acceleration begins. The increase in the mechanical and thermal
energy of the plasma during acceleration is (2-3) × 10<SUP>22</SUP>
ergs. The radial component of the Lorentz force compresses the plasma
during the acceleration process by factors as large as ~100. The
Joule heating flux generated during this process is essentially due
to proton Pedersen current dissipation and can be ~0.1-3.7 times the
heating flux of ~10<SUP>6</SUP> ergs cm<SUP>-2</SUP> s<SUP>-1</SUP>
associated with middle-upper chromospheric emission. About 84%-94%
of the magnetic energy that accelerates and heats the spicules is
converted into bulk flow kinetic energy.
---------------------------------------------------------
Title: Radiating Current Sheets in the Solar Chromosphere
Authors: Goodman, Michael L.; Judge, Philip G.
2012ApJ...751...75G Altcode: 2014arXiv1406.1211G
An MHD model of a hydrogen plasma with flow, an energy equation,
NLTE ionization and radiative cooling, and an Ohm's law with
anisotropic electrical conduction and thermoelectric effects
is used to self-consistently generate atmospheric layers over a
50 km height range. A subset of these solutions contains current
sheets and has properties similar to those of the lower and middle
chromosphere. The magnetic field profiles are found to be close to
Harris sheet profiles, with maximum field strengths ~25-150 G. The
radiative flux F<SUB>R</SUB> emitted by individual sheets is ~4.9 ×
10<SUP>5</SUP>-4.5 × 10<SUP>6</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP>,
to be compared with the observed chromospheric emission rate of
~10<SUP>7</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP>. Essentially all
emission is from regions with thicknesses ~0.5-13 km containing the
neutral sheet. About half of F<SUB>R</SUB> comes from sub-regions with
thicknesses 10 times smaller. A resolution <~ 5-130 m is needed to
resolve the properties of the sheets. The sheets have total H densities
~10<SUP>13</SUP>-10<SUP>15</SUP> cm<SUP>-3</SUP>. The ionization
fraction in the sheets is ~2-20 times larger, and the temperature is
~2000-3000 K higher than in the surrounding plasma. The Joule heating
flux F<SUB>J</SUB> exceeds F<SUB>R</SUB> by ~4%-34%, the difference
being balanced in the energy equation mainly by a negative compressive
heating flux. Proton Pedersen current dissipation generates ~62%-77%
of the positive contribution to F<SUB>J</SUB> . The remainder of this
contribution is due to electron current dissipation near the neutral
sheet where the plasma is weakly magnetized.
---------------------------------------------------------
Title: Radiating Current Sheets in the Solar Chromosphere
Authors: Goodman, Michael L.; Judge, P. G.
2012AAS...22052116G Altcode:
An MHD model of a Hydrogen plasma with flow, an energy equation,
NLTE ionization and radiative cooling, and an Ohm's law with
anisotropic electrical conduction and thermoelectric effects is used
to self-consistently generate atmospheric layers over a 50 km height
range. A subset of these solutions contain current sheets, and have
properties similar to those of the lower and middle chromosphere. The
magnetic field profiles are found to be close to Harris sheet profiles,
with maximum field strengths 25-150 G. The radiative flux F_R emitted
by individual sheets is 4.9 x 10^5 - 4.5 x 10^6 ergs-cm^{-2}-s^{-1},
to be compared with the observed chromospheric emission rate of 10^7
ergs-cm^{-2}-s^{-1}. Essentially all emission is from regions with
thicknesses 0.5 - 13 km containing the neutral sheet. About half of F_R
comes from sub-regions with thicknesses 10 times smaller. A resolution
< 5-130 m is needed to resolve the properties of the sheets. The
sheets have total H densities 10^{13}-10^{15} cm^{-3}. The ionization
fraction in the sheets is 2-20 times larger, and the temperature is
2000-3000 K higher than in the surrounding plasma. The Joule heating
flux F_J exceeds F_R by 4-34 %, the difference being balanced
in the energy equation mainly by a negative compressive heating
flux. Proton Pedersen current dissipation generates 62-77 % of the
positive contribution to F_J. The remainder of this contribution
is due to electron current dissipation near the neutral sheet where
the plasma is weakly magnetized. These solutions represent the first,
first principles theoretical proof of the existence of radiating current
sheets under chromospheric conditions. The existence of these solutions
suggests the existence of sub-resolution, horizontal current sheets
in the chromosphere that are sites of strong Joule heating driven
radiative emission.
---------------------------------------------------------
Title: Conditions for Photospherically Driven Alfvénic Oscillations
to Heat the Solar Chromosphere by Pedersen Current Dissipation
Authors: Goodman, Michael L.
2011ApJ...735...45G Altcode: 2014arXiv1410.8519G
A magnetohydrodynamic model that includes a complete electrical
conductivity tensor is used to estimate conditions for photospherically
driven, linear, non-plane Alfvénic oscillations extending from the
photosphere to the lower corona to drive a chromospheric heating rate
due to Pedersen current dissipation that is comparable to the observed
net chromospheric radiative loss of ~10<SUP>7</SUP> erg cm<SUP>-2</SUP>
s<SUP>-1</SUP>. The heating rates due to electron current dissipation
in the photosphere and corona are also computed. The wave amplitudes
are computed self-consistently as functions of an inhomogeneous
background (BG) atmosphere. The effects of the conductivity
tensor are resolved numerically using a resolution of 3.33 m. The
oscillations drive a chromospheric heating flux F <SUB>Ch</SUB>
~ 10<SUP>7</SUP>-10<SUP>8</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP>
at frequencies ν ~ 10<SUP>2</SUP>-10<SUP>3</SUP> mHz for BG magnetic
field strengths B >~ 700 G and magnetic field perturbation amplitudes
~0.01-0.1 B. The total resistive heating flux increases with ν. Most
heating occurs in the photosphere. Thermalization of Poynting flux
in the photosphere due to electron current dissipation regulates the
Poynting flux into the chromosphere, limiting F <SUB>Ch</SUB>. F
<SUB>Ch</SUB> initially increases with ν, reaches a maximum, and
then decreases with increasing ν due to increasing electron current
dissipation in the photosphere. The resolution needed to resolve the
oscillations increases from ~10 m in the photosphere to ~10 km in the
upper chromosphere and is vpropν<SUP>-1/2</SUP>. Estimates suggest
that these oscillations are normal modes of photospheric flux tubes
with diameters ~10-20 km, excited by magnetic reconnection in current
sheets with thicknesses ~0.1 km.
---------------------------------------------------------
Title: Conditions for Photospherically Driven Aflvenic Oscillations
to Heat the Chromosphere by Pedersen Current Dissipation
Authors: Goodman, Michael L.
2011SPD....42.1704G Altcode: 2011BAAS..43S.1704G
An MHD model that includes a complete electrical conductivity
tensor is used to estimate conditions for photospherically
driven, linear, non-plane Alfvenic oscillations extending from the
photosphere to the lower corona to drive a chromospheric heating
rate due to Pedersen current dissipation that is comparable
to the observed net chromospheric radiative loss of 10<SUP>7
</SUP>ergs-cm<SUP>-2</SUP>-sec<SUP>-1</SUP>. The heating rates due
to electron current dissipation in the photosphere and corona are
also computed. The wave amplitudes are computed self-consistently as
functions of an inhomogeneous background atmosphere. The effects of the
conductivity tensor are resolved numerically using a resolution of 3.33
m. The oscillations drive a chromospheric heating flux F<SUB>Ch</SUB>
10<SUP>7</SUP>-10<SUP>8</SUP> ergs-cm<SUP>-2</SUP>-sec<SUP>-1</SUP>
at frequencies nu 10<SUP>2</SUP> - 10<SUP>3</SUP> mHz for background
magnetic field strengths B > 700 G, and magnetic field perturbation
amplitudes 0.01-0.1 B. The total resistive heating flux increases
with nu. Most heating occurs in the photosphere. Thermalization
of Poynting flux in the photosphere due to electron current
dissipation regulates the Poynting flux into the chromosphere,
limiting F<SUB>Ch</SUB>. F<SUB>Ch</SUB> initially increases with
nu, reaches a maximum, and then decreases with increasing nu due
to increasing electron current dissipation in the photosphere. The
resolution needed to resolve the oscillations increases from 10 m in
the photosphere to 10 km in the upper chromosphere, and is proportional
to nu<SUP>-1/2</SUP>. Estimates suggest these oscillations are normal
modes of photospheric flux tubes with diameters 10-20 km, excited by
magnetic reconnection in current sheets with thicknesses 0.1 km. <P
/>This work was supported by the NSF Solar Terrestrial Physics
Program. It is described in detail in a paper in submission to ApJ.
---------------------------------------------------------
Title: Analytic Solutions for Current Sheet Structure Determined by
Self-consistent, Anisotropic Transport Processes in a Gravitational
Field
Authors: Goodman, Michael L.
2011ApJ...731...19G Altcode:
A Harris sheet magnetic field with maximum magnitude B <SUB>0</SUB> and
length scale L is combined with the anisotropic electrical conductivity,
viscosity, and thermoelectric tensors for an electron-proton plasma to
define a magnetohydrodynamic model that determines the steady state of
the plasma. The transport tensors are functions of temperature, density,
and magnetic field strength, and are computed self-consistently as
functions of position x normal to the current sheet. The flow velocity,
magnetic field, and gravitational force lie along the z-axis. The plasma
is supported against gravity by the viscous force. Analytic solutions
are obtained for temperature, density, and velocity. They are valid
over a broad range of temperature, density, and magnetic field strength,
and so may be generally useful in astrophysical applications. Numerical
examples of solutions in the parameter range of the solar atmosphere
are presented. The objective is to compare Joule and viscous heating
rates, determine the velocity shear that generates viscous forces that
support the plasma and are self-consistent with a mean outward mass flux
comparable to the solar wind mass flux, and compare the thermoelectric
and conduction current contributions to the Joule heating rate. The
ratio of the viscous to Joule heating rates per unit mass can exceed
unity by orders of magnitude, and increases rapidly with L. The viscous
heating rate can be concentrated outside the region where the current
density is localized, corresponding to a resistively heated layer of
plasma bounded by viscously heated plasma. The temperature gradient
drives a thermoelectric current density that can have a magnitude
greater than that of the electric-field-driven conduction current
density, so thermoelectric effects are important in determining the
Joule heating rate.
---------------------------------------------------------
Title: Anisotropic transport processes in the chromosphere and
overlying atmosphere
Authors: Goodman, M. L.; Kazeminezhad, F.
2010MmSAI..81..631G Altcode:
Energy flow and transformation in the solar atmosphere is a complex
process. Fluxes of particle kinetic and electromagnetic energy flow
in both directions through the photosphere, and are transformed
into one another in the overlying atmosphere. Diffusive transport
processes such as electrical and thermal conduction, and viscous and
thermoelectric effects play a major role in determining energy fluxes
and transformation rates. Almost the entire atmosphere is strongly
magnetized, meaning that charged particle cyclotron frequencies
significantly exceed their collision frequencies. This causes transport
processes to be anisotropic, so they must be described by tensors in
MHD models. Only models that include the relevant transport tensors
can reveal the processes that create and maintain the chromosphere,
transition region, and corona because only such models can accurately
describe energy flow and transformation. This paper outlines the
importance of anisotropic transport processes in the atmosphere,
especially of anisotropic electrical conduction in the weakly ionized,
strongly magnetized chromosphere, and presents MHD model evidence
that anisotropic electrical conduction plays a major role in shock
wave and Alfvén wave heating in the chromosphere. It is proposed
that magnetization induced resistivity increases with height from the
photosphere, exceeds the Spitzer resistivity eta <SUB>S</SUB> near
the height of the local temperature minimum, increases with height to
orders of magnitude > eta <SUB>S</SUB>, and causes proton Pedersen
current dissipation to be a major source of chromospheric heating.
---------------------------------------------------------
Title: Simulation of Magnetohydrodynamic Shock Wave Generation,
Propagation, and Heating in the Photosphere and Chromosphere Using
a Complete Electrical Conductivity Tensor
Authors: Goodman, Michael L.; Kazeminezhad, Farzad
2010ApJ...708..268G Altcode:
An electrical conductivity tensor is used in a 1.5D magnetohydrodynamic
(MHD) simulation to describe how MHD shock waves may form, propagate,
and heat the photosphere and chromosphere by compression and resistive
dissipation. The spatial resolution is 1 km. A train of six shock
waves is generated by a sinusoidal magnetic field driver in the
photosphere with a period T = 30 s, mean of 500 G, and variation
of 250 G. The duration of the simulation is 200 s. Waves generated
in the photosphere evolve into shock waves at a height z ~ 375 km
above the photosphere. The transition of the atmosphere from weakly
to strongly magnetized with increasing height causes the Pedersen
resistivity η<SUB> P </SUB> to increase to ~2000 times the Spitzer
resistivity. This transition occurs over a height range of a few hundred
kilometers near the temperature minimum of the initial state at z ~
500 km. The initial state is a model atmosphere derived by Fontenla
et al., plus a background magnetic field. The increase in η<SUB>
P </SUB> is associated with an increase in the resistive heating
rate Q. Shock layer thicknesses are ~10-20 km. They are nonzero due
to the presence of resistive dissipation, so magnetization-induced
resistivity plays a role in determining shock structure, and hence the
compressive heating rate Q<SUB>c</SUB> . At t = 200 s the solution has
the following properties. Within shock layers, Q <SUB>maximum</SUB> ~
1.4-7 erg cm<SUP>-3</SUP> s<SUP>-1</SUP>, and Q <SUB> c,maximum</SUB> ~
10-10<SUP>3</SUP> Q <SUB>maximum</SUB>. Between shock waves, and at some
points within shock layers, Q<SUB>c</SUB> < 0, indicating cooling by
rarefaction. The integrals of Q and Q<SUB>c</SUB> over the shock wave
train are F ~ 4.6 × 10<SUP>6</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP>
and F<SUB>c</SUB> ~ 1.24 × 10<SUP>9</SUP> erg cm<SUP>-2</SUP>
s<SUP>-1</SUP>. A method based on the thermal, mechanical, and
electromagnetic energy conservation equations is presented for checking
the accuracy of the numerical solution, and gaining insight into energy
flow and transformation. The method can be applied to higher dimensional
simulations. It is suggested that observations be performed to map out
the transition region across which the transition from weakly ionized,
weakly magnetized plasma to weakly ionized, strongly magnetized plasma
occurs, and to correlate it with net radiative loss.
---------------------------------------------------------
Title: Models for the Spectral Energy Distibution of Disks at Long
Wavelengths
Authors: Goodman, Michael; Ignace, R.
2010AAS...21542806G Altcode: 2010BAAS...42R.345G
We discuss the spectral energy distributions (SEDs) of axisymmetric
circumstellar disks that produce infrared (IR), millimeter (mm),
and radio emission excesses. In particular, we explore the effects of
disk flaring on the SED shape. We find that relatively mild deviations
from a power-law SED result from flaring. Key diagnostics for assessing
flared disks from the SEDs are highlighted, and applications to IR and
mm spectral measurements for Be star disks are noted. <P />This research
was funded by a grant from the National Science Foundation, AST-0936427.
---------------------------------------------------------
Title: MHD Model Estimates of the Contribution of Driven, Linear,
Non-Plane Wave Dissipation to Chromospheric Heating Using a Complete
Electrical Conductivity Tensor
Authors: Goodman, M. L.
2008AGUFMSH51C..07G Altcode:
Analytic solutions of an MHD model that includes an anisotropic,
inhomogeneous electrical conductivity tensor containing Hall, Pedersen,
and Spitzer conductivities are used to compute resistive heating rates
as a function of height z from the photosphere to the lower corona due
to dissipation of driven, linear, non- plane waves. The background
state of the atmosphere is assumed to be an FAL atmosphere. This
state is linearly perturbed by a harmonic perturbation of frequency
ν. The height dependence of the perturbation in the presence of
the inhomogeneous background state is determined by solving the MHD
equations given the harmonic, horizontal, driving magnetic field
Bx1 at the photosphere, the constant vertical magnetic field Bz,
and the magnetic field strength Bcond(z) that enters the electrical
conductivity tensor. The variation of the heating rates per unit
volume and mass with ν, Bx1, and Bcond(0) are determined. The
heating rates are found to be ∝ Bcond(0)2 Bx12, and to increase with
ν. The Pedersen resistivity is ∝ Bcond(0)2. It is several orders of
magnitude greater than the Spitzer resistivity in the chromosphere, and
determines the rate of heating by Pedersen current dissipation in the
chromosphere. The Pedersen current is essentially a proton current in
the chromosphere. The onset of Pedersen current dissipation rates large
enough to balance the net radiative loss from the chromosphere occurs
near the height of the FAL temperature minimum, and is triggered by
the product of the electron and proton magnetizations first exceeding
unity. The magnetizations and heating rate increase rapidly with
height beginning near the temperature minimum. For the special case
of Bz = 200 G, Bx1=140 G, and 400 ≤ Bcond(0) ≤ 1500 G the driver
frequency for which the period averaged chromospheric heating flux
FCh = 5 × 106 ergs-cm-2-sec-1 has the corresponding range of 91 ≥
ν ≥ 25 mHz. Larger magnetic field strengths correspond to lower
frequencies for a given heating rate. At magnetic field strengths
< 400 G, this value of FCh is achieved only at higher frequencies
corresponding to solutions that violate the linear approximation. For
the similar special case of Bz = 200 G, Bx1=140 G, and 50 ≤ Bcond(0)
≤ 1500 G the range of the maximum allowed driver frequency that is
consistent with the linear approximation is 100.25 ≥ ν ≥ 92.5
mHz. The corresponding range of FCh is 2 × 106 ≤ FCh ≤ 5.4 × 107
ergs-cm-2-sec-1. This raises the possibility that linear MHD waves with
periods ~ 10 seconds might make a major contribution to chromospheric
heating in regions where the photospheric magnetic field strength is
moderate to high. These results support the proposition of Goodman
(e.g. Goodman 2000, ApJ, 533, 501; Goodman 2004, A&A, 424, 691;
Kazeminezhad & Goodman 2006, ApJ, 166, 613) that the onset of
electron and proton magnetization near the local temperature minimum,
and their rapid increase with height causes the rate of proton Pedersen
current dissipation to rapidly increase by orders of magnitude with
height, creating and maintaining the solar chromosphere, and the
chromospheres of solar type stars. This mechanism is not restricted to
linear waves. It operates on any current generating MHD process. This
work was supported by Grant ATM 0650443 from the National Science
Foundation to the West Virginia High Technology Consortium Foundation.
---------------------------------------------------------
Title: MHD Simulations of Shock Wave Generation, Propagation,
and Heating in the Photosphere and Chromosphere Using a Complete
Electrical Conductivity Tensor
Authors: Kazeminezhad, F.; Goodman, M. L.
2008AGUFMSH41A1608K Altcode:
A complete anisotropic, inhomogeneous electrical conductivity tensor,
which includes Spitzer, Pedersen, and Hall conductivities is included in
an MHD simulation to describe how MHD shock waves may form, propagate,
and resistively heat the atmosphere from the photosphere through the
chromosphere. The MHD model includes an energy equation. The initial
state is defined by FAL density, pressure, and temperature profiles, and
by a magnetic field that decreases with height z. The initial magnetic
field strength at the photosphere is 500 G. A harmonic magnetic field
perturbation with amplitude 250 G and period 30 seconds is applied at
the photosphere. Smooth waves are generated at the photosphere that
propagate upward and begin to form shock waves near z=350 km. This
is the height near which electrons first become magnetized. The
shocks become fully formed near the FAL temperature minimum at z=500
km. This is the height where the product of the electron and proton
magnetizations first exceeds unity, causing the Pedersen resistivity to
begin to rapidly exceed the Spitzer resistivity by orders of magnitude
with increasing height. This is also the height at which heating by
proton Pedersen current dissipation rapidly increases with height,
and rapidly becomes large enough to balance the radiative losses from
the chromosphere. The onset of this strong heating is triggered by
the onset of electron and proton magnetization near the temperature
minimum. The shock thicknesses are ~ ~ 5 km. The shocks are the sites
of resistive heating rates as large as 3-10 ergs-cm-3-sec-1 in the
chromosphere. The time averaged heating rate over an interval of
162 seconds corresponds to a chromospheric heating flux ~ 2-3 × 106
ergs-cm-2-sec-1. The heating rate increases with driving frequency,
and is ∝ B2. These results support the proposition of Goodman
(e.g. Goodman 2000, ApJ, 533, 501; Goodman 2004, A&A, 424,691;
Kazeminezhad & Goodman 2006, ApJ, 166, 613) that the onset of
electron and proton magnetization near the local temperature minimum,
and their rapid increase with height causes the rate of proton Pedersen
current dissipation to rapidly increase by orders of magnitude with
height, creating and maintaining the solar chromosphere, and the
chromospheres of solar type stars. This mechanism is not restricted to
shock waves. It operates on any current generating MHD process. Such a
process must involve currents driven by a combination of induction and
convection generated electric fields. Examples are linear waves, and
steady convection across magnetic field lines. It is the weakly ionized,
strongly magnetized nature of the chromosphere that allows this heating
mechanism to be so effective, and that distinguishes the chromosphere
from the weakly ionized, weakly magnetized photosphere, and the strongly
ionized, strongly magnetized corona. The dominance of proton-neutral H
collisions in determining the proton collision frequency is necessary
for this Pedersen current dissipation mechanism to be an effective
heating mechanism in the chromosphere. This work was supported by Grant
ATM 0650443 from the National Science Foundation to the West Virginia
High Technology Consortium Foundation. <P />class="ab'>
---------------------------------------------------------
Title: Magnetohydrodynamic Simulations of Solar Chromospheric Dynamics
Using a Complete Electrical Conductivity Tensor
Authors: Kazeminezhad, Farzad; Goodman, Michael L.
2006ApJS..166..613K Altcode:
A 1.5-dimensional, time-dependent magnetohydrodynamic (MHD) model that
includes an energy equation and anisotropic electrical conductivity
tensor for a variably ionized, multispecies plasma is presented. The
model includes an algorithm that reduces the numerical dissipation
rate far below the dissipation rate determined by the conductivity
tensor. This is necessary for accurate calculation of resistive heating
rates. The model is used to simulate the propagation of Alfvén waves
launched near the base of the middle chromosphere. The background
state is the FAL CM equilibrium with a vertical magnetic field. The
initial magnetic energy of a wave is almost completely damped out in
the chromosphere by the time the disturbance propagates a distance of
one wavelength. The energy is converted mainly into thermal energy. The
remainder is converted into bulk flow kinetic energy and a Poynting
flux with nonzero divergence. The thermal energy is generated almost
entirely by Pedersen current dissipation. The corresponding heating
rates are close to the FAL CM values near the base of the middle
chromosphere. Dynamo action is observed. The damping of a continuously
driven Alfvén wave train is also simulated, yielding results similar
to those of the single wave cases. It is the strong magnetization and
weak ionization of the chromosphere that allows for strong heating
by Pedersen current dissipation. This distinguishes the chromosphere
from the weakly magnetized and weakly ionized photosphere, and the
strongly magnetized and strongly ionized corona where Pedersen current
dissipation is not significant on the length and timescales simulated.
---------------------------------------------------------
Title: Review of Particle Physics
Authors: Yao, W. -M.; Amsler, C.; Asner, D.; Barnett, R. M.; Beringer,
J.; Burchat, P. R.; Carone, C. D.; Caso, C.; Dahl, O.; D'Ambrosio, G.;
De Gouvea, A.; Doser, M.; Eidelman, S.; Feng, J. L.; Gherghetta, T.;
Goodman, M.; Grab, C.; Groom, D. E.; Gurtu, A.; Hagiwara, K.; Hayes,
K. G.; Hernández-Rey, J. J.; Hikasa, K.; Jawahery, H.; Kolda, C.;
Kwon, Y.; Mangano, M. L.; Manohar, A. V.; Masoni, A.; Miquel, R.;
Mönig, K.; Murayama, H.; Nakamura, K.; Navas, S.; Olive, K. A.;
Pape, L.; Patrignani, C.; Piepke, A.; Punzi, G.; Raffelt, G.; Smith,
J. G.; Tanabashi, M.; Terning, J.; Törnqvist, N. A.; sTrippe, T. G.;
Vogel, P.; Watari, T.; Wohl, C. G.; Workman, R. L.; Zyla, P. A.;
Armstrong, B.; Harper, G.; Lugovsky, V. S.; Schaffner, P.; Artuso,
M.; Babu, K. S.; Band, H. R.; Barberio, E.; Battaglia, M.; Bichsel,
H.; Biebel, O.; Bloch, P.; Blucher, E.; Cahn, R. N.; Casper, D.;
Cattai, A.; Ceccucci, A.; Chakraborty, D.; Chivukula, R. S.; Cowan,
G.; Damour, T.; DeGrand, T.; Desler, K.; Dobbs, M. A.; Drees, M.;
Edwards, A.; Edwards, D. A.; Elvira, V. D.; Erler, J.; Ezhela, V. V.;
Fetscher, W.; Fields, B. D.; Foster, B.; Froidevaux, D.; Gaisser,
T. K.; Garren, L.; Gerber, H. -J.; Gerbier, G.; Gibbons, L.; Gilman,
F. J.; Giudice, G. F.; Gritsan, A. V.; Grünewald, M.; Haber, H. E.;
Hagmann, C.; Hinchliffe, I.; Höcker, A.; Igo-Kemenes, P.; JAckson,
J. D.; Johnson, K. F.; Karlen, D.; Kayser, B.; Kirkby, D.; Klein,
S. R.; Kleinknecht, K.; Knowles, I. G.; Kowalewski, R. V.; Kreitz, P.;
Kursche, B.; Kuyanov, Yu. V.; Lahav, O.; Langacker, P.; Liddle, A.;
Ligeti, Z.; Liss, T. M.; Littenberg, L.; Liu, J. C.; Lugovsky, K. S.;
Lugovsky, s. B.; Mannel, T.; Manley, D. M.; Marciano, W. J.; Martin,
A. D.; Milstead, D.; Narain, M.; Nason, P.; Nir, Y.; Peacock, J. A.;
Prell, S. A.; Quadt, A.; Raby, S.; Ratcliff, B. N.; Razuvaev, E. A.;
Renk, B.; Richardson, P.; Roesler, S.; Rolandi, G.; Ronan, M. T.;
Rosenberg, L. J.; Sachrajda, C. T.; Sakai, Y.; Sarkar, S.; Schmitt,
M.; Schneider, O.; Scott, D.; Sjöstrand, T.; Smoot, G. F.; Sokolsky,
P.; Spanier, S.; Spieler, H.; Stahl, A.; Stanev, T.; Streitmatter,
R. E.; Sumiyoshi, T.; Tkachenko, N. P.; Trilling, G. H.; Valencia, G.;
van Bibber, K.; Vincter, M. G.; Ward, D. R.; Webber, B. R.; Wells,
J. D.; Whalley, M.; Wolfenstsein, L.; Womersley, J.; Woody, C. L.;
Yamamoto, A.; Zenin, O. V.; Zhang, J.; Zhu, R. -Y.
2006JPhG...33....1Y Altcode:
This biennial Review summarizes much of particle physics. Using data
from previous editions, plus 2633 new measurements from 689 papers,
we list, evaluate, and average measured properties of gauge bosons,
leptons, quarks, mesons, and baryons. We also summarize searches
for hypothetical particles such as Higgs bosons, heavy neutrinos, and
supersymmetric particles. All the particle properties and search limits
are listed in Summary Tables. We also give numerous tables, figures,
formulae, and reviews of topics such as the Standard Model, particle
detectors, probability, and statistics. Among the 110 reviews are many
that are new or heavily revised including those on CKM quark-mixing
matrix, V<SUB>ud</SUB> & V<SUB>us</SUB>, V<SUB>cb</SUB> &
V<SUB>ub</SUB>, top quark, muon anomalous magnetic moment, extra
dimensions, particle detectors, cosmic background radiation, dark
matter, cosmological parameters, and big bang cosmology. A booklet is
available containing the Summary Tables and abbreviated versions of
some of the other sections of this full Review. All tables, listings,
and reviews (and errata) are also available on the Particle Data Group
website: <A href="http://pdg.lbl.gov">http://pdg.lbl.gov</A>.
---------------------------------------------------------
Title: MHD Simulations of Chromospheric Dynamics Using a Complete
Electrical Conductivity Tensor
Authors: Kazeminezhad, Farzad; Goodman, M.
2006SPD....37.0204K Altcode: 2006BAAS...38R.221K
A 1.5 D MHD simulation that includes an energy equation and a complete
space and timedependent electrical conductivity tensor valid for
a variably ionized plasma is used tostudy Alfven, magnetoacoustic,
and acoustic wave propagation in the chromosphere. Heatingrates due
to dissipation of magnetic field aligned and Pedersen currents are
computed andcompared with FAL values. The model includes a numerical
method that reduces the numerical dissipationrate far below the physical
dissipation rate determined by the conductivity tensor. Wavelengths of
80 - 220 km, and a spatial resolution of 10 km are used. The background
state is the FAL equilibriumstate with a constant vertical magnetic
field. For magnetic waves, the initial energy is converted intothermal
energy, bulk flow kinetic energy, and a Poynting flux of energy
with a non-zero divergence.It is verified that Poynting's theorem is
satisfied. The waves are launched 10^3 km above the FAL photosphere. The
magnetic waves are rapidly damped outnear this height, and produce
heating rates close to the corresponding FAL value. It is the strong
magnetization and weak ionization of the chromospherethat allows for
the strong wave heating. This heating is duealmost entirely to Pedersen
current dissipation.This distinguishes the chromospherefrom the weakly
magnetized and weakly ionized photosphere, and the strongly magnetized
and stronglyionized corona where Pedersen current dissipation is not
a significant heating mechanism on the lengthand time scales simulated.
---------------------------------------------------------
Title: Self-consistent Magnetohydrodynamic Modeling of Current Sheet
Structure and Heating Using Realistic Descriptions of Transport
Processes
Authors: Goodman, Michael L.
2005ApJ...632.1168G Altcode:
A magnetohydrodynamic (MHD) model of an electron-ion,
collision-dominated plasma that includes the electrical conductivity
and thermoelectric tensors in Ohm's law is used to generate current
sheet solutions in parameter ranges that correspond to those of
the solar transition region and lower corona. The model contains
a prescribed sheared magnetic field with a characteristic length
scale L. The characteristic sheet width is 2L, but it is found that
the temperature has transition region or coronal values only within
a diffusion region (DR) with a width several orders of magnitude
smaller than 2L. The heating rate per unit mass and flow speed in
the DR are orders of magnitude larger, and the density is orders of
magnitude smaller than in the surrounding plasma. The heating rate
per unit volume is a maximum in the DR and falls off steadily outside
the DR. The Joule heating rate and current density each consist of a
conduction component driven by the center-of-mass electric field and
a thermoelectric component driven by the temperature gradient. It is
found that these components largely cancel, leading to a total heating
rate and current density orders of magnitude smaller than either of
their components. This suggests that thermoelectric current drive is
important in determining current sheet structure. The center-of-mass
electric field that provides the energy to maintain the plasma in a
steady state is almost entirely the convection electric field. The
electron magnetization M<SUB>e</SUB> is the product of the electron
cyclotron frequency and the electron-ion collision time. Nonzero values
of M<SUB>e</SUB> cause the conductivity and thermoelectric tensors to
be anisotropic. It is found that the large values of M<SUB>e</SUB>
that occur in the DR increase the heating rates per unit volume and
mass by several orders of magnitude and can change the sign of the
heating rate per unit mass from negative to positive, corresponding to
a change from a cooling process to a heating process. This suggests
that electron magnetization, and hence anisotropic transport, is a
major factor in current sheet heating.
---------------------------------------------------------
Title: Megaton Water Cerenkov Detectors and Astrophysical Neutrinos
Authors: Goodman, M.
2005NuPhS.145..335G Altcode: 2005astro.ph..1480G
Although formal proposals have not yet been made, the UNO and
Hyper-Kamiokande projects are being developed to follow-up the
tremendously successful program at Super-Kamiokande using a detector
that is 20-50 times larger. The potential of such a detector to continue
the study of astrophysical neutrinos is considered and contrasted with
the program for cubic kilometer neutrino observatories.
---------------------------------------------------------
Title: Investigation of Solar Coronal Heating Using a Time Dependent
MHD Model with Full Conductivity Tensor
Authors: Kazeminezhad, F.; Goodman, M. L.
2005AGUSMSP41A..07K Altcode:
The transition region and lower corona is investigated using a newly
developed time dependent MHD model that includes gravity and a self
consistently computed conductivity tensor that depends on temperature,
magnetic field, and density. The model is tested by its ability to
preserve FAL equilibrium profiles, and to generate MHD waves with
dispersion relations similar to those predicted by linear theory for
the general types of MHD waves. The model is then used to examine
solar atmospheric heating by Pedersen and magnetic field aligned
current dissipation. Numerical experiments are conducted in which
MHD waves are launched from either the transition region upward,
or from the lower corona downward. Results from parametric studies
of the evolution of these waves as a function of wavelength and
amplitude are presented. In particular, the heating rate due to wave
dissipation is compared with the FAL cooling rate, and with analytic
results presented in M. Goodman [1,2]. % . The relative importance
of physical dissipation due to the conductivity tensor, and numerical
dissipation is estimated using Von Neumann stability analysis (VNSA)
and numerical experiments with and without physical dissipation. It is
then attempted to extrapolate from the simulation data the waves which
could potentially lead to the correct heating rate, assumed to be the
FAL net radiative loss rate. Realistic solar atmospheric data is used
throughout the numerical investigations. This work was supported in
part by NSF grant ATM-0242820 to the Institute for Scientific Research.
---------------------------------------------------------
Title: Chromospheric Heating, Transport Processes, and Small Scale
Magnetic Fields
Authors: Goodman, M. L.
2005AGUSMSH11C..01G Altcode:
There are two basic categories of theories of chromospheric
heating: hydrodynamic heating, and magnetohydrodynamic (MHD)
heating. Hydrodynamic heating by shock wave dissipation appears
to explain the origin of internetwork CaII bright points, but the
associated heating rate appears to be at least one order of magnitude
smaller than what is required to balance the chromospheric net radiative
loss. Heating by high frequency acoustic waves is a proposed mechanism
for chromospheric heating, at least in the internetwork, but so far
there is no observational evidence that the energy in such waves is
sufficient to heat the chromosphere. Increasing observational evidence
for the existence of magnetic field concentrations at or below the
spatial resolution limit with strengths ~ 102 - 103 G, the positive
correlation between magnetic field strength and net radiative loss,
and the differences between network, internetwork, and active regions
in terms of magnetic field filling factor and net radiative loss suggest
that a single MHD mechanism heats the network, internetwork, and active
region chromospheres outside of flaring regions, and operates largely at
or below the spatial resolution limit. A discussion of this suggestion
in the context of the critical need to model proposed chromospheric
heating mechanisms using realistic transport processes is presented
along with an indication of why this heating mechanism is not effective
in the transition region or corona, except possibly on spatial scales
believed to characterize current sheets. This work was supported by
NSF grant ATM-0242820 to the Institute for Scientific Research.
---------------------------------------------------------
Title: Self Consistent Modeling of Current Sheet Structure and
Transport Processes
Authors: Goodman, M. L.
2005AGUSMSP22A..05G Altcode:
A simple magnetohydrodynamic (MHD) model of a fully ionized,
collision dominated plasma that includes the electrical conductivity
and thermoelectric tensors in Ohm's law is used to generate current
sheet solutions that, where the assumption of full ionization is valid,
are characterized by ranges of temperature, density, magnetic field
strength, and flow speed that correspond to those of the transition
region and corona. The electrical conductivity and thermoelectric
tensors are functions of temperature, number density, and magnetic
field strength. The model contains a prescribed sheared magnetic field
with a characteristic length scale L. The characteristic sheet width
is 2L, but the temperature has transition region or coronal values
only within a central plasma sheet (CPS) that has a width one or
more orders of magnitude smaller than 2L. The CPS is essentially the
diffusion region. The heating rate per unit mass, and the flow speed
in the CPS are orders of magnitude larger, and the density is orders of
magnitude smaller than in the surrounding plasma. The heating rate per
unit volume is a maximum in the CPS, and falls off steadily outside
the CPS. The heating is driven almost entirely by the convection
electric field. The current density and heating rate each consist of
a thermoelectric component driven by the temperature gradient, and a
conduction component driven by the center of mass electric field. These
components largely cancel one another, yielding a total current density
and heating rate that are orders of magnitude smaller than either
of their components. This suggests that thermoelectric effects are
important in determing current sheet structure. This work was supported
by NSF grant ATM-0242820 to the Institute for Scientific Research.
---------------------------------------------------------
Title: On the creation of the chromospheres of solar type stars
Authors: Goodman, M. L.
2004A&A...424..691G Altcode:
A mechanism that creates the chromospheres of solar type stars
everywhere outside of flaring regions is proposed. The identification
of the mechanism is based on previous work and on the results of a
model presented here that computes the electric current, its driving
electric field, the heating rate due to resistive dissipation, and
the flow velocity in a specified class of horizontally localized, two
dimensional magnetic structures in the steady state approximation. The
model is applied to the Sun over the height range from the photosphere
to the upper chromosphere. Although the model does not contain time
explicitly, it contains information about the dynamics of the atmosphere
through inputs from the FAL CM solar atmosphere model, which is based on
time averages of spectroscopic data. The model is proposed to describe
the time averaged properties of the heating mechanism that creates the
chromosphere. The model magnetic structure is horizontally localized,
but describes heating of the global chromosphere in the following
way. Recent observations indicate that kilogauss strength magnetic
structures exist in the photospheric internetwork with a filling
factor f∼ 2%, and characteristic diameters < 180 km. Assuming f
= 2 % and a maximum field strength of 10<SUP>3</SUP> G for the model
magnetic structure, and assuming that the chromospheric heating rate
predicted by FAL CM represents a horizontal spatial average over such
magnetic structures, it is found that the model magnetic structures that
best reproduce the FAL CM heating rate as a function of height have
characteristic diameters in the range of 98 - 161 km, consistent with
the upper bound inferred from observation. Based on model solutions
and previous work it is proposed that essentially all chromospheric
heating occurs in magnetic structures with sub-resolution horizontal
spatial scales (⪉ 150 ; km), that the heating is due to dissipation of
Pedersen currents driven by a convection electric field, and that it is
the increase in the magnetization of particles with height in a magnetic
structure from values ≪1 in the lower photosphere to values ⪆1 near
the height of the temperature minimum in the magnetic structure that
causes the Pedersen current dissipation rate to increase to a value
large enough to cause a temperature inversion. The magnetization of a
particle is the ratio of its cyclotron frequency to its total collision
frequency with unlike particle species.
---------------------------------------------------------
Title: Review of Particle Physics
Authors: Particle Data Group; Eidelman, S.; Hayes, K. G.; Olive, K. A.;
Aguilar-Benitez, M.; Amsler, C.; Asner, D.; Babu, K. S.; Barnett,
R. M.; Beringer, J.; Burchat, P. R.; Carone, C. D.; Caso, S.; Conforto,
G.; Dahl, O.; D'Ambrosio, G.; Doser, M.; Feng, J. L.; Gherghetta, T.;
Gibbons, L.; Goodman, M.; Grab, C.; Groom, D. E.; Gurtu, A.; Hagiwara,
K.; Hernández-Rey, J. J.; Hikasa, K.; Honscheid, K.; Jawahery, H.;
Kolda, C.; Kwon, Y.; Mangano, M. L.; Manohar, A. V.; March-Russell,
J.; Masoni, A.; Miquel, R.; Mönig, K.; Murayama, H.; Nakamura, K.;
Navas, S.; Pape, L.; Patrignani, C.; Piepke, A.; Raffelt, G.; Roos, M.;
Tanabashi, M.; Terning, J.; Törnqvist, N. A.; Trippe, T. G.; Vogel,
P.; Wohl, C. G.; Workman, R. L.; Yao, W. -M.; Zyla, P. A.; Armstrong,
B.; Gee, P. S.; Harper, G.; Lugovsky, K. S.; Lugovsky, S. B.; Lugovsky,
V. S.; Rom, A.; Artuso, M.; Barberio, E.; Battaglia, M.; Bichsel, H.;
Biebel, O.; Bloch, P.; Cahn, R. N.; Casper, D.; Cattai, A.; Chivukula,
R. S.; Cowan, G.; Damour, T.; Desler, K.; Dobbs, M. A.; Drees, M.;
Edwards, A.; Edwards, D. A.; Elvira, V. D.; Erler, J.; Ezhela, V. V.;
Fetscher, W.; Fields, B. D.; Foster, B.; Froidevaux, D.; Fukugita,
M.; Gaisser, T. K.; Garren, L.; Gerber, H. -J.; Gerbier, G.; Gilman,
F. J.; Haber, H. E.; Hagmann, C.; Hewett, J.; Hinchliffe, I.; Hogan,
C. J.; Höhler, G.; Igo-Kemenes, P.; Jackson, J. D.; Johnson, K. F.;
Karlen, D.; Kayser, B.; Kirkby, D.; Klein, S. R.; Kleinknecht, K.;
Knowles, I. G.; Kreitz, P.; Kuyanov, Yu. V.; Lahav, O.; Langacker,
P.; Liddle, A.; Littenberg, L.; Manley, D. M.; Martin, A. D.;
Narain, M.; Nason, P.; Nir, Y.; Peacock, J. A.; Quinn, H. R.; Raby,
S.; Ratcliff, B. N.; Razuvaev, E. A.; Renk, B.; Rolandi, G.; Ronan,
M. T.; Rosenberg, L. J.; Sachrajda, C. T.; Sakai, Y.; Sanda, A. I.;
Sarkar, S.; Schmitt, M.; Schneider, O.; Scott, D.; Seligman, W. G.;
Shaevitz, M. H.; Sjöstrand, T.; Smoot, G. F.; Spanier, S.; Spieler,
H.; Spooner, N. J. C.; Srednicki, M.; Stahl, A.; Stanev, T.; Suzuki,
M.; Tkachenko, N. P.; Trilling, G. H.; Valencia, G.; van Bibber, K.;
Vincter, M. G.; Ward, D. R.; Webber, B. R.; Whalley, M.; Wolfenstein,
L.; Womersley, J.; Woody, C. L.; Zenin, O. V.; Zhu, R. -Y.
2004PhLB..592....1P Altcode: 2004PhLB..592....1E
No abstract at ADS
---------------------------------------------------------
Title: On the Creation of the Chromospheres of Solar Type Stars
Authors: Goodman, M. L.
2004AAS...204.2904G Altcode: 2004BAAS...36..695G
A mechanism that creates the chromospheres of solar type stars
everywhere outside of flaring regions is presented. The identification
of the mechanism is based on previous work and on the results of a
model presented here that computes the flow velocity, electric current,
its driving electric field, and the heating rate due to resistive
dissipation in a specified class of horizontally localized, two
dimensional magnetic structures in the steady state approximation. The
model is applied to the Sun over the height range from the photosphere
to the upper chromosphere. Although the model does not contain time
explicitly, it contains information about the dynamics of the atmosphere
through inputs from the FAL CM solar atmosphere model, which is based on
time averages of spectroscopic data. The model is proposed to describe
the time averaged properties of the heating mechanism that creates the
chromosphere. The model predicts that essentially all chromospheric
heating occurs in magnetic structures with sub-resolution horizontal
spatial scales, that the heating is due to dissipation of Pedersen
currents driven by a convection electric field, and that it is the
increase in the magnetization of particles with height in a magnetic
structure from values << 1 in the lower photosphere to values ≳
1 near the height of the temperature minimum in the magnetic structure
that causes the Pedersen current dissipation rate to increase to a value
large enough to cause a temperature inversion. The magnetization of a
particle is the ratio of its cyclotron frequency to its total collision
frequency with unlike particle species. The model magnetic structure is
horizontally localized, but is used to describe heating of the global
chromosphere in the following way. Recent observations indicate that
kilogauss strength magnetic structures exist in the photospheric
internetwork with a filling factor f ∼ 2 %, and characteristic
diameters < 180 km. Assuming f = 2 % and a maximum field strength of
10<SUP>3</SUP> G for the model magnetic structure, and assuming that the
chromospheric heating rate predicted by FAL CM represents a horizontal
spatial average over such magnetic structures, it is found that the
model magnetic structures that best reproduce the FAL CM heating rate
as a function of height have characteristic diameters in the range of
98 - 161 km, consistent with the upper bound inferred from observation.
---------------------------------------------------------
Title: On the efficiency of plasma heating by Pedersen current
dissipation from the photosphere to the lower corona
Authors: Goodman, M. L.
2004A&A...416.1159G Altcode:
A model is presented that uses the electrical conductivity tensor of
a multi-species plasma to estimate the efficiency Q of plasma heating
by Pedersen current dissipation as a function of height from the
photosphere to the lower corona. The particle densities and temperature
are given by FAL model CM. Q is the efficiency with which the electric
field generates thermal energy by transferring energy to the current
density J<SUB>⊥</SUB> perpendicular to the magnetic field. The energy
is then thermalized by collisions. The projection of J<SUB>⊥</SUB>
on the driving electric field is the Pedersen current density. Q
is the ratio of the actual heating rate due to Pedersen current
dissipation to the heating rate when J<SUB>⊥</SUB> is entirely a
Pedersen current, which is the maximum possible heating rate for given
J<SUB>⊥</SUB>. It is found that Pedersen current dissipation is highly
efficient throughout the chromosphere, but is highly inefficient in the
transition region and corona on the spatial scales of FAL CM. In the
photosphere, the electron magnetization, which is the product of the
cyclotron frequency and the collision time is so small compared to unity
that the conductivity tensor is almost isotropic, implying there is no
essential difference between Pedersen current dissipation and magnetic
field aligned current dissipation. It is the rapid increase with height
of the magnetizations of electrons, protons and metallic ions from
≲ 1 to ≫ 1 beginning near the height of the FAL CM temperature
minimum that causes Pedersen current dissipation to become essentially
different from magnetic field aligned current dissipation, and that
causes Q to rapidly increase from minimum values ∼ 0.1 near the
temperature minimum to ∼ 1 in the lower chromosphere. Q remains ∼
1 up to the transition region in which it precipitously decreases with
height to values ≲ 10<SUP>-10</SUP> in the corona. It is proposed that
the rapidly increasing magnetization triggers the onset of heating by
Pedersen current dissipation that causes the chromospheric temperature
inversion and heats the entire non-flaring chromosphere. The energy
channeled by any mechanism into the generation of a center of mass
(CM) electric field that drives current perpendicular to the magnetic
field is thermalized by Pedersen current dissipation at the maximum
possible rate throughout the chromosphere. The mechanism is damped
in the chromosphere to the degree to which its energy is channeled
into the creation of the CM electric field. The results of the model
are consistent with previous predictions that slow magnetoacoustic
waves heat network regions of the chromosphere through dissipation
of Pedersen currents driven by a wave generated convection electric
field, and that electric current dissipation on the spatial scales of
the FAL models is insignificant for heating the transition region.
---------------------------------------------------------
Title: Physical Modeling of the Solar Radiation, Current Status
and Prospects
Authors: Fontenla, J. M.; Avrett, E. H.; Goodman, M.; White, O. W.;
Rottman, G.; Fox, P.; Harder, J.
2003SPD....34.0301F Altcode: 2003BAAS...35..808F
Physical models that include full NLTE radiative transfer as well as
particle transport and MHD processes are the key to understanding the
solar radiative output and also are essential to our understanding
of heating and the dynamics of the solar atmosphere, in particular
for chromospheric layers. SOHO observations show that chromospheric
emission lines do not vary dramatically in time and that chromospheric
heating, even in the quiet Sun, is not simply due to, p-modes induced,
strong shock waves passing through the chromosphere. The physics of
the chromospheric heating is more complicated and remains elusive. The
chromospheric and coronal heating are likely closely related to the
dynamics in these regions as well as in the thin chromosphere-corona
transition region since they are a coupled system. Solar atmospheric
heating and dynamics are strongly affected by the magnetic fields and
MHD mechanisms must be considered. Models for the upper photosphere
and chromosphere should also consider NLTE radiative transfer and
radiative losses as well as particle transport processes including
tensor electric resistivity with magnetic field. Models for the
transition region and coronal layers must also consider particle
diffusion. In this paper we show schematically: 1) the current state
of our research on modeling observed features of the solar structure
and their radiative signatures; 2) the application of this modeling
to the Earth solar irradiance and comparisons with observations; 3)
the key achievements and the needed improvements of the modeling; 4)
our plans for future research starting from ab initio semi-empirical
models based on observations, and, while maintaining the agreement with
relevant observations, moving towards physically consistent models that
include key MHD processes thereby replacing empirical constraints by
physically consistent processes and boundary conditions.
---------------------------------------------------------
Title: Predictions of Heating Rates in Localized Magnetic Structures
From The Photosphere To The Upper Chromosphere
Authors: Goodman, M. L.
2003SPD....34.1105G Altcode: 2003BAAS...35R.827G
The heating rates due to resistive dissipation of magnetic field
aligned currents and of Pedersen currents are computed as functions
of height and horizontal radius in a specified 2.5 D magnetic field
from the photosphere to the upper chromosphere. The model uses the
VAL C height dependent profiles of temperature, and electron, proton,
hydrogen, helium, and heavy ion densities together with the magnetic
field to compute the anisotropic electrical conductivity tensor for each
charged particle species. The magnetic field is parameterized by its
maximum magnitude B<SUB>0</SUB>, scale height L, characteristic diameter
D<SUB>0</SUB>, and twist τ which is the ratio of the azimuthal field
component to the radial field component. The objective is to determine
the ranges of values of these parameters that yield heating rates that
are within observational constraints for values of D<SUB>0</SUB> that
are above and below the resolution limit of ∼ 150 km. This provides
a test of the proposition that Pedersen current dissipation is a major
source of chromopsheric heating in magnetic structures throughout the
chromosphere, and that it is the rapid increase of charged particle
magnetization with height in the lower chromosphere that causes the
chromospheric temperature inversion and the rapid increase of the
heating rate per unit mass with height in this region. It is found
that the heating rate is a monotonically increasing function of
B<SUB>0,</SUB> L, and τ , and a monotonically decreasing function
of D<SUB>0</SUB>. For values of D<SUB>0</SUB> below the resolution
limit, values of τ >> 1 correspond to strongly heated magnetic
structures. <P />This work was supported by NSF grant ATM 9816335.
---------------------------------------------------------
Title: Overview of Future Neutrino Experiments
Authors: Goodman, M.
2003psc..confE..66G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Plasma Heating by Pedersen Current Dissipation From the
Photosphere to the Upper Chromosphere
Authors: Goodman, M. L.
2002AGUFMSH52A0477G Altcode:
An MHD model is used to estimate the contribution of Pedersen
current dissipation, as a function of height z, to plasma heating
from the photosphere to the upper chromosphere. The model computes the
particle diffusion velocities, normalized to the local drift velocity,
transverse to a vertical magnetic field for a seven species plasma of
electrons, protons, a proxy heavy ion, HeI, HeII, HeIII, and H. The
proxy heavy ion is a single species representation of singly ionized C,
Si, Al, Mg, Fe, Na, and Ca. The temperature and particle densities as
functions of z are given by VAL model C. Collisions between all unlike
particle species are taken into account. The diffusion velocities are
used to compute the heating rate per unit volume Q(z), normalized
to the maximum possible heating rate per unit volume at height z,
due to Pedersen current dissipation. Q is the fraction of energy
in the current density perpendicular to the magnetic field that
is dissipated by collisions. Solutions to the model suggest that:
(i) The solar chromosphere above photospheric magnetic fields with
strengths ~ 10<SUP>2</SUP> - 10<SUP>3</SUP> G is heated by Pedersen
current dissipation; (ii) This heating mechanism first becomes
effective at heights corresponding to the lower chromosphere as
defined by VAL; (iii) It is the rapid increase of charged particle
magnetization with height in the lower chromosphere that triggers
the rapid onset of intense heating by Pedersen current dissipation,
where the magnetization is the ratio of the cyclotron frequency to the
total collision frequency with unlike particles; (iv) Q(z) rapidly
decreases to zero for z > ~ 2100 km due to strong magnetization
transforming the current perpendicular to the magnetic field into a
Hall current, which is not dissipative; (v) The protons and the proxy
heavy ions carry essentially all of the Pedersen current. These results
suggest that network and internetwork regions of the chromosphere are
heated by Pedersen current dissipation. The model does not assume or
predict any form for the mechanism that drives the heating. However,
the results of the model are consistent with previous predictions that
magnetoacoustic waves heat network regions of the chromosphere through
Pedersen current dissipation driven by a wave generated convection
electric field. It is proposed that this wave heating mechanism also
makes a major contribution to heating internetwork regions of the
chromosphere. This work was supported by National Science Foundation
grant ATM 9816335.
---------------------------------------------------------
Title: Atmospheric Neutrinos in Soudan 2
Authors: Goodman, M.; Soudan 2 Collaboration
2001ICRC....3.1085G Altcode: 2001ICRC...27.1085G
Neutrino interactions recorded in a 5.1 fiducial kiloton-year exposure
of the Soudan-2 iron tracking calorimeter are analyzed for effects of
neutrino oscillations. Using contained single track and single shower
events, we update our measurement of the atmospheric / ratio-of-ratios
and find . Assuming this anomalously low R-value is the result of
flavor disappearance viat o oscillation, we select samples of charged
current events which offer good resolution, event-by-event, for Ä
reconstruction. Oscillation-weighted Monte Carlo events are fitted
to these data events using a ¾ function summed over bins of log´Ä
µ. The region allowed in the (× Ò¾ ¾ , ¡Ñ¾) plane at 90% CL is
obtained using the Feldman-Cousins procedure: 1 DETECTOR; DATA EXPOSURE
The Soudan-2 experiment will soon (July 2001) be completing the taking
of data using its fine-grained iron tracking calorimeter of total mass
963 tons. This detector images nonrelativistic as well as relativistic
charged particles produced in atmospheric neutrino reactions. It
has operated underground at a depth of 2100 meters-water-equivalent
on level 27 of the Soudan Mine State Park in northern Minnesota. The
calorimeter's modular design enabled data-taking to commence in April
1989 when the detector was one quarter of its full size; assembly of
the detector was completed during 1993. Data-taking continued with 85%
live time, even though dynamite blasting has been underway nearby for
the MINOS cavern excavation since Summer 1999. The total data exposure
will be 5.8fiducial kiloton-years (kTy). Results presented here are
based upon a 5.1 kTy exposure. The tracking calorimeter operates as a
slow-drift (0.6 cm/ s) time projection chamber. Its tracking elements
are meterlong plastic drift tubes which are placed into the corruga-
---------------------------------------------------------
Title: Search for Nucleon Decay and n-nbar Oscillation in Soudan 2
Authors: Chung, J.; Fields, T.; Goodman, M.
2001ICRC....4.1463C Altcode: 2001ICRC...27.1463C
We have studied multiprong contained events in the Soudan 2 detector
in order to search for nucleon decay and neutron oscillation (and
subsequent annihilation) into high multiplicity final states. The
excellent spatial resolution of the Soudan 2 tracking calorimeter
detector, together with its capability to identify slow proton tracks
and stopping tracks through their higher ionization, enables us to
analyze high multiplicity events in more detail than has been done
previously. We have found no evidence for signal events above the
(small) estimated backgroundof multiprong events due to atmospheric
neutrino interactions.
---------------------------------------------------------
Title: Horizontal Muons in Soudan 2 and Search for AGN Neutrinos
Authors: Demuth, D.; Goodman, M.
2001ICRC....3.1089D Altcode: 2001ICRC...27.1089D
Using horizontal muons in Soudan 2, we measure the neutrino induced muon
flux and set a limit on the flux of neutrinos from AGN's. A horizontal
neutrino induced flux of 5.00 ± 0.55 ± 0.51 ×10-13 cm-2 sr-1 s-1
is measured. The absence of horizontal muons with a large energy loss
is used to set a limit on the flux of ν's from AGN's as a function
of energy.
---------------------------------------------------------
Title: The Necessity of Using Realistic Descriptions of Transport
Processes in Modeling the Solar Atmosphere, and the Importance of
Understanding Chromospheric Heating*
Authors: Goodman, Michael L.
2001SSRv...95...79G Altcode:
Three points and research directions are discussed: The outstanding
problem of identifying the mechanisms of solar atmospheric heating
and wind acceleration can be solved only by combining quantitative
models that include realistic descriptions of relevant transport
processes with observational constraints on the inputs and outputs
of these models. Most solar atmospheric heating, with the possible
exception of flares, takes place in the chromosphere, emphasizing the
importance of identifying the mechanisms of chromospheric heating,
which may be important for understanding coronal heating and wind
acceleration. Recent modeling leads to the conclusion that the onset
of proton magnetization with increasing height in thin magnetic flux
tubes triggers the onset of chromospheric network heating by resistive
dissipation of Pedersen currents driven by the convection electric
field of slow, longitudinal magnetoacoustic waves.
---------------------------------------------------------
Title: Proton Magnetization as the Triggering Mechanism for
Chromospheric Network Heating by Pedersen Current Dissipation
Authors: Goodman, M. L.
2000SPD....31.0140G Altcode: 2000BAAS...32..808G
In thin magnetic flux tubes in the photospheric and lower chromospheric
network, the product ω τ of the proton cyclotron frequency with
the proton-hydrogen collision time increases with height. Near the
photosphere (ω τ )<SUP>2</SUP> << 1 in strong magnetic flux
tubes. Near the height of the temperature minimum, which is different
for flux tubes with different photospheric field strengths, (ω τ
)<SUP>2</SUP> ~ 1. When (ω τ )<SUP>2</SUP> increases through unity
the protons are said to become magnetized: at this height control
of the proton dynamics switches from collisions with hydrogen to the
magnetic field. This causes a rapid increase in the rate of Pedersen
current dissipation, determined by the rapid change in the anisotropic
conductivity tensor for a weakly ionized plasma of hydrogen, electrons,
protons, and singly ionized heavy ions. The rapid increase of heating
rate with height just above the temperature minimum in a flux tube
is due to the continuing increase of proton magnetization with
height, and to the following feedback mechanism: heating by Pedersen
current dissipation ---> increase in hydrogen ionization --->
increase in ratio of proton number density to heavy ion number density
---> increase in heating by Pedersen current dissipation. Above
the temperature minimum the heating rate increases by one order of
magnitude over one pressure scale height. The classical concept of
a single temperature minimum about 500 km above the photosphere is
interpreted as an average over the heights of the different temperature
minima of different flux tubes. Ranges of hydrogen density and magnetic
field strength for the lower chromospheric network are predicted. The
current density is driven by slow, longitudinal, magnetoacoustic
waves that have their source in the dynamic interaction between the
photospheric granulation and the magnetic flux tubes concentrated at
the granulation boundaries. The author gratefully acknowledges support
by NSF grant ATM-9816335 to the Catholic University of America.
---------------------------------------------------------
Title: On the Mechanism of Chromospheric Network Heating and the
Condition for Its Onset in the Sun and Other Solar-Type Stars
Authors: Goodman, Michael L.
2000ApJ...533..501G Altcode:
A mechanism for chromospheric network heating and a necessary and
sufficient condition for its onset are presented. The heating
mechanism consists of resistive dissipation of proton Pedersen
currents, which flow orthogonal to the magnetic field in weakly
ionized chromospheric plasma. The currents are driven by a convection
electric field generated by velocity oscillations of linear, slow,
longitudinal magnetoacoustic waves with frequencies ν<~3.5 mHz
in the lower chromosphere. The heating occurs in thin magnetic flux
tubes and begins lower in the chromosphere in flux tubes with higher
photospheric field strength. The lower chromosphere, which emits most
of the net radiative loss in the network, is heated by flux tubes with
photospheric field strengths ~700-1500 G. A typical field strength and
core diameter for a flux tube in the lower chromosphere with a core
heating rate of 10<SUP>7</SUP> ergs cm<SUP>-2</SUP> s<SUP>-1</SUP>
are 170 G and 10 km. This core region is contained in a region with
a diameter ~100 km in which the heating rate is an order of magnitude
smaller. About N~10<SUP>2</SUP> of these flux tubes distributed over
the boundary region of a granule with a diameter ~10<SUP>3</SUP> km
provide an average heating rate over the entire granule ~10<SUP>7</SUP>
ergs cm<SUP>-2</SUP> s<SUP>-1</SUP>. If the core heating rate is
changed by a factor f, then N~f<SUP>-1/2</SUP>10<SUP>2</SUP>. The
condition for the onset of heating is that the ratio of the proton
cyclotron frequency to the proton-hydrogen collision frequency equal
unity. This ratio increases with height, and the condition is satisfied
at a single height in a given flux tube. At this height, control of the
proton dynamics begins to be dominated by the magnetic field rather
than by collisions with hydrogen, and the anisotropic nature of the
electrical conductivity begins to play a critical role in resistive
dissipation. The protons become magnetized. Heating by dissipation of
heavy ion and, to a lesser extent, proton Pedersen currents causes
the temperature to start increasing. The heating increases hydrogen
ionization. With increasing height, and hence proton magnetization,
the Pedersen current density rapidly increases with hydrogen ionization
via positive feedback, and the proton number density rapidly reaches
and exceeds the heavy ion number density, resulting in an increase
in heating rate by an order of magnitude over only 1 pressure scale
height. During this process the protons rapidly dominate the Pedersen
current. Heating by dissipation of magnetic field aligned currents is
insignificant. Below the height in the atmosphere at which the onset
condition is satisfied, any current orthogonal to the magnetic field
must be primarily a Hall current, which is nondissipative. Heating by
this mechanism must occur to some degree in the chromospheric network
of all solar-type stars. It is proposed to be the dominant mechanism of
chromospheric network heating, although viscous dissipation may also be
important if the core heating rate is much larger than ~10<SUP>7</SUP>
ergs cm<SUP>-2</SUP> s<SUP>-1</SUP> or if the linear MHD waves studied
here evolve into shock waves with increasing height. Flux tubes in the
quiet chromosphere are predicted to have two possible core diameters:
~10 km, corresponding to flux tubes in which network heating occurs,
and ~10<SUP>4</SUP>-10<SUP>5</SUP> km, perhaps corresponding to flux
tubes in which active region heating might occur. The model has a
singularity at the acoustic cutoff frequency, corresponding to periods
near 3 minutes. Therefore, unless nonresistive damping mechanisms such
as viscous dissipation and thermal conduction provide sufficiently
strong damping, MHD oscillations with periods near 3 minutes in
chromospheric magnetic flux tubes must be nonlinear.
---------------------------------------------------------
Title: On the Mechanism of Chromospheric Network Heating, and the
Condition for its Onset in the Sun and Other Solar Type Stars
Authors: Goodman, M. L.
1999AAS...194.2307G Altcode: 1999BAAS...31..861G
A mechanism for chromospheric network heating, and a necessary and
sufficient condition for its onset are presented. The heating mechanism
consists of resistive dissipation of proton Pedersen currents, which
flow orthogonal to the magnetic field in weakly ionized chromospheric
plasma. The currents are driven by a convection electric field generated
by velocity oscillations of linear magnetoacoustic waves with periods
greater than about 5 minutes. Heating occurs in thin magnetic flux
tubes, and begins lower in the chromosphere in flux tubes with higher
photospheric field strength. The lower chromosphere, which emits most of
the chromospheric radiation, is heated by flux tubes with photospheric
field strengths in the range of 700 - 1500 G. A typical diameter and
field strength for a heated flux tube in the lower chromosphere are 10
km and 100 G. The condition for the onset of this heating mechanism
is that the proton cyclotron frequency equal the proton-hydrogen
collision frequency. When this occurs, heating by dissipation of
heavy ion Pedersen currents begins to raise the gas temperature, and
hydrogen ionization increases exponentially with temperature according
to the Saha equation. The Pedersen current density rapidly increases
as the proton number density rapidly reaches and exceeds the heavy
ion number density, resulting in an increase in heating rate by an
order of magnitude over a height increase of only one pressure scale
height. During this process the protons rapidly dominate the Pedersen
current. This heating mechanism and condition for its onset apply
to all solar type stars: stars with a convection zone and associated
dynamo action causing the formation of photospheric convection cells
with strong magnetic field concentrations at their boundaries.
---------------------------------------------------------
Title: Quantitative Magnetohydrodynamic Modeling of the Solar
Transition Region
Authors: Goodman, Michael L.
1998ApJ...503..938G Altcode:
The transition region (TR) is assumed to be a collision-dominated
plasma. The dissipation and transport of energy in such a plasma
is accurately described by the classical transport coefficients,
which include the electrical and thermal conductivity, viscosity,
and thermoelectric tensors. These tensors are anisotropic and are
functions of local values of temperature, density, and magnetic field
strength. The transport coefficients are valid for all magnetic
field strengths and so may be used to study the physics of weakly
as well as strongly magnetized regions of the TR. They may be used
in an MHD model to obtain a self-consistent, realistic description
of the TR. The physics of kinetic processes is included in the MHD
model through the transport coefficients. As a first step in studying
heating and cooling processes in the TR in a realistic, quantitative
manner, a 1.5 dimensional, steady state MHD model with a specified
temperature profile is developed. The momentum equation includes
the inertial, pressure, magnetic, and gravitational forces. Ohm's
law includes the exact expressions for the electrical conductivity
and thermoelectric tensors. It is found that the contribution of the
dissipation of large-scale electric currents to in situ heating of
the TR is negligible, but that thermal energy flowing into the TR
from the corona can provide the energy required to heat the TR. The
possibility that significant in situ heating of the TR takes place
through viscous dissipation or small-scale electric current dissipation
such as may occur in current sheets or filaments is discussed, although
these processes are not described by the model. The importance of
thermoelectric and electron pressure gradient effects in Ohm's law,
and in determining the electron heat flux, is demonstrated. Results of
the model suggest that the force-free approximation is not valid over
most of the TR. Justification for assuming that the TR is collision
dominated is presented. In particular, a self-consistent calculation
of the ratio of the electric field parallel to the magnetic field to
the Dreicer electric field yields a value <~10<SUP>-3</SUP>, which
suggests that anomalous transport processes are not important. The
necessity of using a realistic description of transport processes in
modeling heating mechanisms in the solar atmosphere is stressed.
---------------------------------------------------------
Title: Convection driven heating of the solar middle chromosphere
by resistive dissipation of large scale electric currents. II.
Authors: Goodman, M. L.
1997A&A...325..341G Altcode:
A generalization of a recently developed MHD model of a proposed
heating mechanism for the middle chromosphere is presented. The
generalization consists of including the ideal gas equation of state,
allowing the temperature to vary with position, and allowing the
hydrogen flow velocity to vary with height in a specified manner. These
generalizations allow for a self consistent calculation of a temperature
profile. The variation of the flow velocity with height generates a
component of the inertial force which adds to the vertical gradient
of the thermal pressure in supporting the plasma against gravity. This
allows for a lower temperature for a given number density. The solutions
presented suggest that resistively heated magnetic loops embedded in
a much stronger, larger scale potential field, and having horizontal
spatial scales of several thousand kilometers provide the thermal energy
necessary to heat the middle chromosphere on these spatial scales. For
these solutions the temperature is in the range of 6000-8700K,
consistent with the temperature range in the middle chromosphere. The
magnetic loops have one footpoint region where the field is strongest
and directed mainly upward, and where the heating rates per unit mass
and volume are small. The field lines extend upward from this region at
the base of the middle chromosphere, diverge horizontally, and return to
a footpoint region at the base of the middle chromosphere as a weaker,
more diffuse, mainly downward directed field. In this footpoint region
the heating rates are also small. The heating rates are largest in the
middle of the loops. For the magnetic loops considered, the temperature
shows little horizontal variation between the footpoint region where
the field is strongest and the heating rates are small, and the region
where the heating rates are largest. This suggests that large horizontal
variations in the net radiative loss from heated magnetic loops may not
always be associated with large horizontal variations in temperature.
---------------------------------------------------------
Title: Convection driven heating of the solar middle chromosphere
by resistive dissipation of large scale electric currents.
Authors: Goodman, M. L.
1997A&A...324..311G Altcode:
A two dimensional, steady state, resistive magnetohydrodynamic (MHD)
model with flow is used to support the proposition that a major
source of heating for the solar middle chromosphere is resistive
dissipation of large scale electric currents driven by a convection
electric field. The currents are large scale in that their scale
heights range from hundreds of kilometers in the network to thousands
of kilometers in the internetwork. The current is carried by protons,
and flows orthogonal to the magnetic field in a weakly ionized, strongly
magnetized hydrogen plasma. The flow velocity is mainly parallel to
the magnetic field. The relatively small component of flow velocity
orthogonal to the magnetic field generates a convection electric field
which drives the current. The magnetic field is the sum of a loop
shaped field, called a magnetic element, and a much stronger, larger
scale potential field. All of the heating takes place in the magnetic
element. Solutions to the model indicate that magnetic elements with
horizontal spatial extents of about one thousand to five thousand
kilometers may be confined to, and heat, the middle chromospheric
network. Other solutions to the model indicate that magnetic elements
with horizontal spatial extents of about ten thousand to thirty thousand
kilometers may span and heat the middle chromospheric internetwork,
and may be the building blocks of the chromospheric magnetic canopy. It
is suggested that the middle chromosphere is highly structured over
a wide range of spatial scales determined by the properties of these
magnetic elements, and stronger, larger scale potential fields.
---------------------------------------------------------
Title: MHD Modeling of the Transition Region Using Realistic Transport
Coefficients
Authors: Goodman, Michael L.
1997SPD....28.0604G Altcode: 1997BAAS...29..910G
Most of the transition region (TR) consists of a collision dominated
plasma. The dissipation and transport of energy in such a plasma
is accurately described by the well known classical transport
coefficients which include the electrical and thermal conductivity,
viscosity, and thermo- electric tensors. These tensors are anisotropic
and are functions of local values of temperature, density, and
magnetic field. They may be used in an MHD model to obtain a self
consistent, physically realistic description of the TR. The physics of
kinetic processes is included in the MHD model through the transport
coefficients. As a first step in studying heating and cooling processes
in the TR in a realistic, quantitative manner, a 1.5 dimensional, steady
state MHD model with a specified temperature profile is considered. The
momentum equation includes the inertial, pressure gradient, Lorentz,
and gravitational forces. The Ohm's law includes the exact expressions
for the electrical conductivity and thermo- electric tensors. The
electrical conductivity relates the generalized electric field to the
conduction current density while the thermo-electric tensor relates
the temperature gradient to the thermo-electric current density. The
total current density is the sum of the two. It is found that the
thermo-electric current density can be as large as the conduction
current density, indicating that thermo-electric effects are probably
important in modeling the dynamics of energy dissipation, such as
wave dissipation, in the TR. Although the temperature gradient is
in the vertical direction, the thermo-electric current density is in
the horizontal direction, indicating the importance of the effects of
anisotropic transport. The transport coefficients are valid for all
magnetic field strengths, and so may be used to study the physics of
weakly as well as strongly magnetized regions of the TR. Numerical
examples are presented.
---------------------------------------------------------
Title: Heating of the Solar Middle Chromospheric Network and
Internetwork by Large-Scale Electric Currents in Weakly Ionized
Magnetic Elements
Authors: Goodman, Michael L.
1996ApJ...463..784G Altcode:
A two-dimensional, dissipative magnetohydrodynamic model is used to
argue that a major source of in situ heating for the solar middle
chromosphere is the resistive dissipation of large-scale electric
currents flowing in magnetic elements. A magnetic element is an
arch-shaped magnetic field configuration consisting of a central
region of horizontally localized, mainly vertical magnetic field
based in the photosphere, with field lines that diverge horizontally
with increasing height, extend into the middle chromosphere, and then
return to the photo sphere as a relatively diffuse, weaker field. The
currents that flow in these elements are carried by protons, and are
large scale in that their scale height is hundreds of kilometers in
the network and thousands of kilometers in the internetwork. Solutions
to the model demonstrate that the resistive dissipation of large-scale
electric currents flowing orthogonal to the magnetic field in magnetic
elements embedded in a weakly ionized, strongly magnetized hydrogen
gas may generate all of the thermal energy necessary to heat the middle
chromosphere. The magnetic field is computed self-consistently with the
electric field, pressure, and hydrogen and proton densities. Solutions
to the model suggest that magnetic elements with horizontal extents up
to several arcseconds may be confined to, and heat, the chromospheric
network, while elements with the largest horizontal extents may span and
heat the internetwork and be the building blocks of the chromospheric
magnetic canopy. The model predicts that the heating rate per unit mass
(q) is independent of height, peaked near but horizontally displaced
from the center of a magnetic element, and for realistic model input
parameters has an average value computed over the base area of the
element dose to the value 4.5 x 10<SUP>9</SUP> ergs g<SUP>-1</SUP>
s<SUP>-1</SUP> predicted by semiempirical models of the chromosphere
that also predict that q is independent of height in the middle
chromosphere. The model predicts that the heating rate per unit volume
is peaked near the horizontal midpoint of a magnetic element where
the field is mainly horizontal. The model predicts that both heating
rates are zero at the center and outer boundary of a magnetic element
where the field is vertical. These model predictions for the spatial
localization of the heating rates are consistent with observations
that regions of enhanced emission are near but horizontally displaced
from regions of vertical, high-magnitude magnetic field.
---------------------------------------------------------
Title: Convection Driven Heating of the Solar Middle Chromosphere
by Large Scale Electric Currents
Authors: Goodman, M. L.
1996AAS...188.3607G Altcode: 1996BAAS...28..874G
A two dimensional, steady state, resistive MHD model with flow is
used to support the proposition that a major source of heating for the
solar middle chromosphere is the resistive dissipation of large scale
electric currents driven by a convection electric field. The currents
are large scale in the sense that their scale heights range from
hundreds of kilometers in the network to thousands of kilometers in the
internetwork. The current is carried by protons, and flows orthogonal
to the magnetic field which is embedded in a weakly ionized, strongly
magnetized hydrogen plasma. The resistive dissipation is determined by
the Pedersen resistivity. The flow velocity is mainly parallel to the
magnetic field, but the relatively small component of flow velocity
orthogonal to the magnetic field generates a convection electric field
which drives the current. The magnetic field is the sum of a loop shaped
field, and a much stronger, larger scale potential field. The heating
takes place in the region occupied by the loop field which is only a few
gauss while the potential field is close to 200 G. Hence magnetometer
observations may suggest that the total field is potential while
radiation intensity observations indicate the presence of mechanical
heating. Solutions to the model indicate that magnetic elements with
horizontal spatial extents of ~ 1 - 5 thousand kilometers may be
confined to, and heat, the middle chromospheric network. Solutions to
the model also indicate that magnetic elements with horizontal spatial
extents of ~ 10 - 30 thousand kilometers may span and heat the middle
chromospheric internetwork region over the interior of supergranules,
and may be the building blocks of the chromospheric magnetic canopy.
---------------------------------------------------------
Title: A three-dimensional, iterative mapping procedure for the
implementation of an ionosphere-magnetosphere anisotropic Ohm's law
boundary condition in global magnetohydrodynamic simulations
Authors: Goodman, Michael L.
1995AnGeo..13..843G Altcode: 1995AnG....13..843G
The mathematical formulation of an iterative procedure for the numerical
implementation of an ionosphere-magnetosphere (IM) anisotropic Ohm's
law boundary condition is presented. The procedure may be used in
global magnetohydrodynamic (MHD) simulations of the magnetosphere. The
basic form of the boundary condition is well known, but a well-defined,
simple, explicit method for implementing it in an MHD code has not been
presented previously. The boundary condition relates the ionospheric
electric field to the magnetic field-aligned current density driven
through the ionosphere by the magnetospheric convection electric field,
which is orthogonal to the magnetic field B, and maps down into the
ionosphere along equipotential magnetic field lines. The source of
this electric field is the flow of the solar wind orthogonal to B. The
electric field and current density in the ionosphere are connected
through an anisotropic conductivity tensor which involves the Hall,
Pedersen, and parallel conductivities. Only the height-integrated
Hall and Pedersen conductivities (conductances) appear in the final
form of the boundary condition, and are assumed to be known functions
of position on the spherical surface R=R1 representing the boundary
between the ionosphere and magnetosphere. The implementation presented
consists of an iterative mapping of the electrostatic potential
<psi>, the gradient of which gives the electric field,
and the field-aligned current density between the IM boundary at
R=R1 and the inner boundary of an MHD code which is taken to be at
R<SUB>2</SUB>>R<SUB>1</SUB>. Given the field-aligned current density
on R=R<SUB>2</SUB>, as computed by the MHD simulation, it is mapped
down to R=R<SUB>1</SUB> where it is used to compute <psi> by
solving the equation that is the IM Ohm's law boundary condition. Then
<psi> is mapped out to R=R<SUB>2</SUB>, where it is used to
update the electric field and the component of velocity perpendicular
to <strong>B</strong>. The updated electric field and
perpendicular velocity serve as new boundary conditions for the MHD
simulation which is then used to compute a new field-aligned current
density. This process is iterated at each time step. The required Hall
and Pedersen conductances may be determined by any method of choice,
and may be specified anew at each time step. In this sense the coupling
between the ionosphere and magnetosphere may be taken into account in
a self-consistent manner.
---------------------------------------------------------
Title: Heating of the Solar Middle Chromosphere by Large-Scale
Electric Currents
Authors: Goodman, M. L.
1995ApJ...443..450G Altcode:
A global resistive, two-dimensional, time-dependent magnetohydrodynamic
(MHD) model is used to introduce and support the hypothesis that the
quiet solar middle chromosphere is heated by resistive dissipation
of large-scale electric currents which fill most of its volume. The
scale height and maximum magnitude of the current density are 400 km
and 31.3 m/sq m, respectively. The associated magnetic field is almost
horizontal, has the same scale height as the current density, and has
a maximum magnitude of 153 G. The current is carried by electrons
flowing across magnetic field lines at 1 m/s. The resistivity is
the electron contribution to the Pedersen resitivity for a weakly
ionized, strongly magnetized, hydrogen gas. The model does not include
a driving mechanism. Most of the physical quantities in the model
decrease exponentially with time on a resistive timescale of 41.3
minutes. However, the initial values and spatial; dependence of these
quantities are expected to be essentially the same as they would be if
the correct driving mechanism were included in a more general model. The
heating rate per unit mass is found to be 4.5 x 10<SUP>9</SUP>
ergs/g/s, independent of height and latitude. The electron density
scale height is found to be 800 km. The model predicts that 90% of the
thermal energy required to heat the middle chromosphere is deposited
in the height range 300-760 km above the temperature minimum. It is
shown to be consistent to assume that the radiation rate per unit
volume is proportional to the magnetic energy density, and then it
follows that the heating rate per unit volume is also proportional to
the energy from the photosphere into the overlying chromosphere are
briefly discussed as possible driving mechanisms for establishing and
maintaining the current system. The case in which part of or all of the
current is carried by protons and metal ions, and the contribution of
electron-proton scattering to the current are also considered, with the
conclusion that these effects do not change the qualitative prediction
of the model, but probably change the quantitative predictions slightly,
mainly by increasing the maximum magntiude of the current density and
magnetic field to at most approximately 100 mA/m and approximately 484
G, respectively. The heating rate per unit mass, current density scale
height, magnetic field scale height, temperatures, and pressures are
unchanged or are only slightly changed by including these additional
effects due to protons and ions.
---------------------------------------------------------
Title: Neutrino Oscillation Experiments with Atmospheric Neutrinos
Authors: Gaisser, T.; Goodman, M.
1995pnac.conf..220G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Long-Baseline Neutrino Oscillation Experiments
Authors: Crane, D.; Goodman, M.
1995pnac.conf..225C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Long-baseline neutrino oscillation experiments
Authors: Crane, D.; Goodman, M.
1994panm.conf.....C Altcode:
There is no unambiguous definition for long baseline neutrino
oscillation experiments. The term is generally used for accelerator
neutrino oscillation experiments which are sensitive to Delta sq m
less than 1.0 eV<SUP>2</SUP>, and for which the detector is not on the
accelerator site. The Snowmass N2L working group met to discuss the
issues facing such experiments. The Fermilab Program Advisory Committee
adopted several recommendations concerning the Fermilab neutrino program
at their Aspen meeting immediately prior to the Snowmass Workshop. This
heightened the attention for the proposals to use Fermilab for a
long-baseline neutrino experiment at the workshop. The plan for
a neutrino oscillation program at Brookhaven was also thoroughly
discussed. Opportunities at CERN were considered, particularly the
use of detectors at the Gran Sasso laboratory. The idea to build a
neutrino beam from KEK towards Superkamiokande was not discussed at
the Snowmass meeting, but there has been considerable development of
this idea since then. Brookhaven and KEK would use low energy neutrino
beams, while FNAL and CERN would plan have medium energy beams. This
report will summarize a few topics common to LBL proposals and attempt
to give a snapshot of where things stand in this fast developing field.
---------------------------------------------------------
Title: Driven, dissipative, energy-conserving magnetohydrodynamic
equilibria. Part 2. The screw pinch
Authors: Goodman, Michael L.
1993JPlPh..49..125G Altcode:
A cylindrically symmetric, electrically driven, dissipative,
energy-conserving magnetohydrodynamic equilibrium model is
considered. The high-magneticfield Braginskii ion thermal conductivity
perpendicular to the local magnetic field and the complete electron
resistivity tensor are included in an energy equation and in
Ohm's law. The expressions for the resistivity tensor and thermal
conductivity depend on number density, temperature, and the poloidal
and axial (z-component) magnetic field, which are functions of radius
that are obtained as part of the equilibrium solution. The model has
plasma-confining solutions, by which is meant solutions characterized
by the separation of the plasma into two concentric regions separated
by a transition region that is an internal boundary layer. The inner
region is the region of confined plasma, and the outer region is
the region of unconfined plasma. The inner region has average values
of temperature, pressure, and axial and poloidal current densities
that are orders of magnitude larger than in the outer region. The
temperature, axial current density and pressure gradient vary rapidly
by orders of magnitude in the transition region. The number density,
thermal conductivity and Dreicer electric field have a global minimum
in the transition region, while the Hall resistivity, Alfvén speed,
normalized charge separation, Debye length, (ωλ)<SUB>ion</SUB>
and the radial electric field have global maxima in the transition
region. As a result of the Hall and electron-pressure-gradient
effects, the transition region is an electric dipole layer in which
the normalized charge separation is localized and in which the radial
electric field can be large. The model has an intrinsic value of β,
about 13·3%, which must be exceeded in order that a plasma-confining
solution exist. The model has an intrinsic length scale that, for
plasma-confining solutions, is a measure of the thickness of the
boundary-layer transition region. If appropriate boundary conditions
are given at R = 0 then the equilibrium is uniquely determined. If
appropriate boundary conditions are given at any outer boundary R
= a then the equilibrium exhibits a bifurcation into two states,
one of which exhibits plasma confinement and carries a larger axial
current than the other, which is almost homogeneous and cannot confine
a plasma. Exact expressions for the two values of the axial current in
the bifurcation are derived. If the boundary conditions are given at R =
a then a solution exists if and only if the constant driving electric
field exceeds a critical value. An exact expression for this critical
electric field is derived. It is conjectured that the bifurcation is
associated with an electric-field-driven transition in a real plasma,
between states with different rotation rates, energy dissipation rates
and confinement properties. Such a transition may serve as a relatively
simple example of the L—H mode transition observed in tokamaks.
---------------------------------------------------------
Title: On driven, dissipative, energy-conserving magnetohydrodynamic
equilibria
Authors: Goodman, Michael L.
1992JPlPh..48..177G Altcode:
A cylindrically symmetric, electrically driven, dissipative,
energy-conserving magnetohydrodynamic equilibrium model is
considered. The high-magnetic-field Braginskii electron electrical
resistivity η parallel to a constant axial magnetic field B and
ion thermal conductivity ĸ perpendicular to B are included in an
energy equation and in Ohm's law. The expressions for η and ĸ
depend on number density and temperature, which are functions of
radius that are obtained as part of the equilibrium solution. The
model has plasma-confining solutions, by which are meant solutions
characterized by the separation of the plasma into two regions separated
by a relatively thin transition region that is an internal boundary
layer across which temperature and current density vary rapidly. The
inner region has a temperature, pressure and current density that are
much larger than in the outer region. The number density and thermal
conductivity attain their minimum values in the transition region. The
model has an intrinsic value of β, about 6.6%, which must be exceeded
in order that a plasma-confining solution exist. The model has an
intrinsic length scale, which, for plasma-confining solutions, is a
measure of the thickness of the transition region separating the inner
and outer regions of plasma. A larger class of transport coefficients
is modelled by artificially changing η and ĸ by changing the constant
coefficients η<SUB>O</SUB> and ĸ<SUB>O</SUB> that occur in their
expressions. Increasing ĸ<SUB>O</SUB> transforms a state that does
not exhibit confinement into one that does, improves the confinement
in a state that already exhibits it, and leads to an increase in ĸ in
the confined region of plasma. The improvement in confinement consists
in a decrease in the thickness of the transition region. Decreasing
η<SUB>O</SUB> subject to certain constraints, also transforms a state
that does not exhibit confinement into one that does, improves the
confinement in a state that already exhibits it, and leads to a decrease
in η in the confined region of plasma. Increasing η<SUB>O</SUB> up to
a critical point increases the current, temperature, and volume of the
confined region of plasma, and causes the thickness of the transition
region to increase. If η<SUB>O</SUB> is increased beyond the critical
point, a plasma-confining state cannot exist. In all cases it is found
that an increase in ĸ and a decrease in η in the confined region of
plasma are associated with an improvement in the confinement properties
of the equilibrium state. If the pressure and temperature are given on
the cylinder wall, the equilibrium bifurcates when the electric field
decreases below a critical value. The equilibrium can bifurcate into
a state that exhibits confinement and a state that does not.
---------------------------------------------------------
Title: Coincidences between extensive air showers and the Soudan 1
underground muon detector
Authors: Das Gupta, U.; Border, P.; Johns, K.; Longley, N.; Marshak,
M.; Peterson, E.; Ruddick, K.; Shupe, M.; Ayres, D.; Dawson, J.;
Fields, T.; Goodman, M.; May, E.
1992PhRvD..45.1459D Altcode:
We have operated the Soudan 1 underground muon detector in coincidence
with a 36-m<SUP>2</SUP> detector situated at the Earth's surface. Such
a combination of detectors can yield information on the composition
of the primary cosmic rays at energies above ~3×10<SUP>15</SUP>
eV, where there is an abrupt change in the slope of the energy
spectrum. The present experiment was meant to test the feasibility of
operating such a system, and to obtain a first sample of data before
the complete installation of the much larger Soudan 2 detector. These
initial data seem to favor a light composition in the energy range
10<SUP>15</SUP>-10<SUP>16</SUP> eV, but there are significant systematic
uncertainties.
---------------------------------------------------------
Title: Combination of Probabilities in Looking for Cosmic Ray Sources
Authors: Goodman, M.
1991ICRC....2..660G Altcode: 1991ICRC...22b.660G
No abstract at ADS
---------------------------------------------------------
Title: Signals from cosmic ray sources, some statistical issues
Authors: Goodman, M.
1990hep..conf.....G Altcode:
The possible existence of discrete sources of cosmic rays is presently
one of the main topics of study in non-accelerator particle physics. The
search is being conducted in a wide variety of experiments using
UHE gamma rays, VHE gamma rays, EeV particles, underground mu's and
nu's. The current experimental situation, however, can be described as
chaotic. The number of claimed observations of sources by different
groups using a variety of experimental techniques is quite large,
but a consistent interpretation of the various results has failed
to emerge. Most of the observations rely on either a dc excess from
the direction of the source, a periodicity of the events from that
direction, or some combination of these two effects. In the first
section of this paper, we discuss some of the techniques that may be
used in searching for a dc excess. We review two common bin free tests
of the light curves. We discuss a particular problem involving phase
coherence when doing a period search. This paper discusses some of
the issues and meanings involved in combining probabilities from more
than one test. Prescribing the right way to do analysis is certainly
beyond this paper's scope. However some of the issues and problems
are considered here.
---------------------------------------------------------
Title: Cosmic ray air showers in a fine grained calorimeter.
Authors: Goodman, M.
1986isos.book..568G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An Experimental Study of Hadrons and Muons Near Shower Cores
Using the E-594 Neutrino Detector at Fermilab
Authors: Goodman, J. A.; Tonwar, S. C.; Yodh, G. B.; Ellsworth,
R. W.; Goodman, M.; Bogert, D.; Brock, R.; Burnstein, R.; Fuess, S.;
Morfin, J.; Peters, M.; Stutte, L.; Walter, J. K.; Bofill, J.; Busza,
W.; Friedman, J.; Lyons, T.; Mattison, T.; Osborne, L. B.; Pitt, R.;
Rosenson, L.; Sandacz, A.; Tartaglia, M.; Whitaker, S.; Yeh, G. P.;
Abolins, M.; Cohen, A.; Owen, D.; Slate, J.; Taylor, F. E.; Mukherjee,
A.; Eldridge, T.; Magahiz, R.
1983ICRC...11..248G Altcode: 1983ICRC...18k.248G; 1983icrc...11..248G
The E-594 neutrino detector has been used to study the lateral
distribution of hadrons and muons near shower cores. The detector
consists of a 340-ton fine-grain calorimeter with 400,000 cells of
flash chamber and dimensions 3.7 x 20 x 3.7 m (height). The average
density of absorber in the calorimeter is 1.4 g/sq cm and the average
Z is 21. A 5-day run was taken on cosmic-ray data using a trigger
provided by four 0.6-sq m plastic scintillation counters located above
the calorimeter. A shower density of eight particles/sq m was required
to trigger. These data were studied to determine the number of muons
traversing the device as a function of electron density. Preliminary
results of this study are compared to Monte Carlo simulations of air
showers from hadrons of 1-10 PeV.
---------------------------------------------------------
Title: An Experimental Study of Hadrons and Muons Near Shower Cores
Using the E-594 Neutrino Detector at Fermilab
Authors: Yodh, G. B.; Goodman, J. A.; Tonwar, S. C.; Ellsworth, R. W.;
Goodman, M.
1983ICRC....6...70Y Altcode: 1983ICRC...18f..70Y
No abstract at ADS
