Particle interactions with single or multiple 3D solar reconnecting current sheets

TL;DR

This study models charged particle acceleration in solar active regions through stochastic interactions with magnetic reconnection sites, analyzing energy gains and distributions in different topologies via numerical experiments.

Contribution

It introduces a generalized formula for energy gain at X-points and demonstrates the invariant form of energy distribution after few steps in multiple reconnection scenarios.

Findings

Energy distribution becomes invariant after few steps.

Generalized energy gain formula for X-points.

Mean acceleration time and pitch angle distributions provided.

Abstract

The acceleration of charged particles (electrons and protons) in flaring solar active regions is analyzed by numerical experiments. The acceleration is modelled as a stochastic process taking place by the interaction of the particles with local magnetic reconnection sites via multiple steps. Two types of local reconnecting topologies are studied: the Harris-type and the X-point. A formula for the maximum kinetic energy gain in a Harris-type current sheet, found in a previous work of ours, fits well the numerical data for a single step of the process. A generalization is then given approximating the kinetic energy gain through an X-point. In the case of the multiple step process, in both topologies the particles' kinetic energy distribution is found to acquire a practically invariant form after a small number of steps. This tendency is interpreted theoretically. Other characteristics of the acceleration process are given, such as the mean acceleration time and the pitch angle distributions of the particles.