Fast electron slowing-down and diffusion in a high temperature coronal X-ray source

Galloway, R.K., MacKinnon, A.L. , Kontar, E.P. and Helander, P. (2005) Fast electron slowing-down and diffusion in a high temperature coronal X-ray source. Astronomy and Astrophysics, 438(3), pp. 1107-1114. (doi: 10.1051/0004-6361:20042137)




Finite thermal velocity modifications to electron slowing-down rates may be important for the deduction of solar flare total electron energy. Here we treat both slowing-down and velocity diffusion of electrons in the corona at flare temperatures, for the case of a simple, spatially homogeneous source. Including velocity diffusion yields a consistent treatment of both "accelerated" and "thermal" electrons. It also emphasises that one may not invoke finite thermal velocity target effects on electron lifetimes without simultaneously treating the contribution to the observed X-ray spectrum from thermal electrons. We present model calculations of the X-ray spectra resulting from injection of a power-law energy distribution of electrons into a source with finite temperature. Reducing the power-law distribution low-energy cutoff to lower and lower energies only increases the relative magnitude of the thermal component of the spectrum, because the lowest energy electrons simply join the background thermal distribution. Acceptable fits to RHESSI flare data are obtained using this model. These also demonstrate, however, that observed spectra may in consequence be acceptably consistent with rather a wide range of injected electron parameters.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Kontar, Professor Eduard and MacKinnon, Dr Alexander
Authors: Galloway, R.K., MacKinnon, A.L., Kontar, E.P., and Helander, P.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Astronomy and Astrophysics
Publisher:EDP Sciences
Copyright Holders:Copyright © 2005 EDP Sciences
First Published:First published in Astronomy and Astrophysics 438(3):1107-1114
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher
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