Particle acceleration and radiation in flaring complex solar active regions modeled by cellular automata

Abstract

Context. We study the acceleration and radiation of electrons and ions interacting with multiple small-scale dissipation regions resulting from the magnetic energy release process. Aims. We aim to calculate the distribution functions of the kinetic energy of the particles and the X-ray spectra and γ-ray fluxes produced by the accelerated particles. Methods. The evolution of the magnetic energy released in an active region is mimicked by a cellular automaton model based on the concept of self-organized criticality. Each burst of magnetic energy release is associated with a reconnecting current sheet (RCS) in which the particles are accelerated by a direct electric field. Results. We calculate the energy gain of the particles (ions and electrons) for three different magnetic configurations of the RCS after their interactions with a given number of RCS. We finally compare our results with existing observations. Conclusions. The results of our simulation can reproduce several properties of the observations such as variable electron and ion energy contents and γ-ray line ratio. Even if very flat X-ray spectra have been reported in a few events, the X-ray spectra produced in this model are too flat when compared to most X-ray observations.