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Title: THREE-DIMENSIONAL SIMULATIONS OF GYROSYNCHROTRON EMISSION FROM MILDLY ANISOTROPIC NONUNIFORM ELECTRON DISTRIBUTIONS IN SYMMETRIC MAGNETIC LOOPS

Abstract

Microwave emission of solar flares is formed primarily by incoherent gyrosynchrotron radiation generated by accelerated electrons in coronal magnetic loops. The resulting emission depends on many factors, including pitch-angle distribution of the emitting electrons and the source geometry. In this work, we perform systematic simulations of solar microwave emission using recently developed tools (GS Simulator and fast gyrosynchrotron codes) capable of simulating maps of radio brightness and polarization as well as spatially resolved emission spectra. A three-dimensional model of a symmetric dipole magnetic loop is used. We compare the emission from isotropic and anisotropic (of loss-cone type) electron distributions. We also investigate effects caused by inhomogeneous distribution of the emitting particles along the loop. It is found that the effect of the adopted moderate electron anisotropy is the most pronounced near the footpoints and it also depends strongly on the loop orientation. Concentration of the emitting particles at the looptop results in a corresponding spatial shift of the radio brightness peak, thus reducing effects of the anisotropy. The high-frequency ({approx}> 50 GHz) emission spectral index is specified mainly by the energy spectrum of the emitting electrons; however, at intermediate frequencies (around 10-20 GHz), the spectrum shape is strongly dependent onmore » the electron anisotropy, spatial distribution, and magnetic field nonuniformity. The implications of the obtained results for the diagnostics of the energetic electrons in solar flares are discussed.« less

Authors:
 [1]; ;  [2]
  1. Armagh Observatory, Armagh BT61 9DG (United Kingdom)
  2. Center for Solar-Terrestrial Research, New Jersey Institute of Technology, Newark, NJ 07102 (United States)
Publication Date:
OSTI Identifier:
22004626
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 742; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; BRIGHTNESS; COMPUTERIZED SIMULATION; EMISSION SPECTRA; ENERGY SPECTRA; INCLINATION; LOSS CONE; MAGNETIC FIELDS; MICROWAVE RADIATION; SOLAR CORONA; SOLAR FLARES; SPATIAL DISTRIBUTION; SUN; SYMMETRY; TAIL ELECTRONS; THREE-DIMENSIONAL CALCULATIONS

Citation Formats

Kuznetsov, Alexey A, Nita, Gelu M, and Fleishman, Gregory D. THREE-DIMENSIONAL SIMULATIONS OF GYROSYNCHROTRON EMISSION FROM MILDLY ANISOTROPIC NONUNIFORM ELECTRON DISTRIBUTIONS IN SYMMETRIC MAGNETIC LOOPS. United States: N. p., 2011. Web. doi:10.1088/0004-637X/742/2/87.
Kuznetsov, Alexey A, Nita, Gelu M, & Fleishman, Gregory D. THREE-DIMENSIONAL SIMULATIONS OF GYROSYNCHROTRON EMISSION FROM MILDLY ANISOTROPIC NONUNIFORM ELECTRON DISTRIBUTIONS IN SYMMETRIC MAGNETIC LOOPS. United States. https://doi.org/10.1088/0004-637X/742/2/87
Kuznetsov, Alexey A, Nita, Gelu M, and Fleishman, Gregory D. 2011. "THREE-DIMENSIONAL SIMULATIONS OF GYROSYNCHROTRON EMISSION FROM MILDLY ANISOTROPIC NONUNIFORM ELECTRON DISTRIBUTIONS IN SYMMETRIC MAGNETIC LOOPS". United States. https://doi.org/10.1088/0004-637X/742/2/87.
@article{osti_22004626,
title = {THREE-DIMENSIONAL SIMULATIONS OF GYROSYNCHROTRON EMISSION FROM MILDLY ANISOTROPIC NONUNIFORM ELECTRON DISTRIBUTIONS IN SYMMETRIC MAGNETIC LOOPS},
author = {Kuznetsov, Alexey A and Nita, Gelu M and Fleishman, Gregory D},
abstractNote = {Microwave emission of solar flares is formed primarily by incoherent gyrosynchrotron radiation generated by accelerated electrons in coronal magnetic loops. The resulting emission depends on many factors, including pitch-angle distribution of the emitting electrons and the source geometry. In this work, we perform systematic simulations of solar microwave emission using recently developed tools (GS Simulator and fast gyrosynchrotron codes) capable of simulating maps of radio brightness and polarization as well as spatially resolved emission spectra. A three-dimensional model of a symmetric dipole magnetic loop is used. We compare the emission from isotropic and anisotropic (of loss-cone type) electron distributions. We also investigate effects caused by inhomogeneous distribution of the emitting particles along the loop. It is found that the effect of the adopted moderate electron anisotropy is the most pronounced near the footpoints and it also depends strongly on the loop orientation. Concentration of the emitting particles at the looptop results in a corresponding spatial shift of the radio brightness peak, thus reducing effects of the anisotropy. The high-frequency ({approx}> 50 GHz) emission spectral index is specified mainly by the energy spectrum of the emitting electrons; however, at intermediate frequencies (around 10-20 GHz), the spectrum shape is strongly dependent on the electron anisotropy, spatial distribution, and magnetic field nonuniformity. The implications of the obtained results for the diagnostics of the energetic electrons in solar flares are discussed.},
doi = {10.1088/0004-637X/742/2/87},
url = {https://www.osti.gov/biblio/22004626}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 742,
place = {United States},
year = {Thu Dec 01 00:00:00 EST 2011},
month = {Thu Dec 01 00:00:00 EST 2011}
}