Electron acceleration and radiation in evolving complex active regions

¹ National Observatory of Athens, Institute for Space Applications and Remote Sensing, 152 36 Penteli, Greece
² Research Center for Astronomy and Applied Mathematics, Academy of Athens, Greece e-mail: cgontik@cc.uoa.gr
³ LESIA, Observatoire de Paris-Meudon, 92195 Meudon Cedex, France e-mail: nicole.vilmer@obspm.fr
⁴ Department of Physics, University of Thessaloniki, 54124 Thessaloniki, Greece e-mail: vlahos@astro.auth.gr

Corresponding author: A. Anastasiadis, anastasi@space.noa.gr

Received: 19 November 2003
Accepted: 26 March 2004

Abstract

We present a model for the acceleration and radiation of solar energetic particles (electrons) in evolving complex active regions. The spatio – temporal evolution of active regions is calculated using a cellular automaton model, based on self-organized criticality. The acceleration of electrons is due to the presence of randomly placed, localized electric fields produced by the energy release process, simulated by the cellular automaton model. We calculate the resulting kinetic energy distributions of the particles and their emitted X-ray radiation spectra using the thick target approximation, and we perform a parametric study with respect to number of electric fields present and thermal temperature of the injected distribution. Finally, comparing our results with the existing observations, we find that they are in a good agreement with the observed X-ray spectra in the energy range 100–1000 keV.