An Analytical Model for the Propagation of Thermal Runaway Electrons in Solar Flares

The nature of the hard X-ray emission from solar flares is well known. The observed emission in both the corona and the chromosphere consists of two components: nonthermal and thermal. The non-thermal and thermal components are attributable to the bremsstrahlung of accelerated electrons and heated p...

Full description

Saved in:
Bibliographic Details
Published in:Astronomy letters 2019-04, Vol.45 (4), p.237-247
Main Authors: Gritsyk, P. A., Somov, B. V.
Format: Article
Language:English
Subjects:
Astronomy
Astrophysics and Astroparticles
Atmospheric evolution
Atmospheric models
Bremsstrahlung
Chromosphere
Corona
Coulomb collisions
Distribution functions
Electrons
Emission spectra
Emissions
Exact solutions
Kinetic equations
Magnetic reconnection
Mathematical models
Model accuracy
Observations and Techniques
Physics
Physics and Astronomy
Propagation
Solar atmosphere
Solar flares
Thermal runaway
X-ray emissions
X-ray spectra
Citations: Items that this one cites
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The nature of the hard X-ray emission from solar flares is well known. The observed emission in both the corona and the chromosphere consists of two components: nonthermal and thermal. The non-thermal and thermal components are attributable to the bremsstrahlung of accelerated electrons and heated plasma electrons, respectively. Since the nonthermal and thermal hard X-ray emission spectra partially overlap, their proper interpretation directly depends on the accuracy of the kinetic models describing the propagation of thermal and nonthermal runaway electrons in the solar atmosphere. The evolution of the distribution function for the latter, i.e., the electrons accelerated in the magnetic reconnection region, is accurately described in the approximation of present-day thick-target models with a reverse current. Here we consider a model for the thermal runaway of electrons and find an analytical solution of the corresponding kinetic equation in which the Coulomb collisions are taken into account. The degree of polarization of the emission has been estimated to be no greater than ∼5%. The derived distribution function can also be used to calculate the thermal X-ray emission spectrum and, as a consequence, to interpret the observations of the thermal component in the X-ray spectrum of a solar flare.
ISSN:1063-7737
1562-6873
DOI:10.1134/S1063773719040030