Collisional relaxation of electrons in a warm plasma and accelerated nonthermal electron spectra in solar flares

Kontar, Eduard P., Jeffrey, Natasha, Emslie, A. Gordon and Bian, N. H. (2015) Collisional relaxation of electrons in a warm plasma and accelerated nonthermal electron spectra in solar flares. The Astrophysical Journal, 809 (1). p. 35. ISSN 0004-637X

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Official URL: https://doi.org/10.1088/0004-637x/809/1/35

Abstract

Extending previous studies of nonthermal electron transport in solar flares, which include the effects of collisional energy diffusion and thermalization of fast electrons, we present an analytic method to infer more accurate estimates of the accelerated electron spectrum in solar flares from observations of the hard X-ray spectrum. Unlike for the standard cold-target model, the spatial characteristics of the flaring region, especially the necessity to consider a finite volume of hot plasma in the source, need to be taken into account in order to correctly obtain the injected electron spectrum from the source-integrated electron flux spectrum (a quantity straightforwardly obtained from hard X-ray observations). We show that the effect of electron thermalization can be significant enough to nullify the need to introduce an ad hoc low-energy cutoff to the injected electron spectrum in order to keep the injected power in non-thermal electrons at a reasonable value. Rather, the suppression of the inferred low-energy end of the injected spectrum compared to that deduced from a cold-target analysis allows the inference from hard X-ray observations of a more realistic energy in injected non-thermal electrons in solar flares.

Item Type: Article
Uncontrolled Keywords: Sun: corona, Sun: flares, Sun: X-rays, gamma-rays
Subjects: F300 Physics
F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Elena Carlaw
Date Deposited: 09 Sep 2019 15:03
Last Modified: 11 Oct 2019 13:01
URI: http://nrl.northumbria.ac.uk/id/eprint/40606

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