Particle acceleration at a reconnecting magnetic separator

TL;DR

This paper investigates how magnetic separator reconnection in the solar corona can accelerate particles, using simulations to analyze effects of initial conditions and model parameters on particle energies, aligning results with observed spectra.

Contribution

It introduces a detailed study of particle acceleration at magnetic separators using a relativistic guiding-centre code within a time-dependent reconnection model, an area previously underexplored.

Findings

Particle energies achieved match observed spectra.

Initial conditions significantly influence acceleration outcomes.

Model parameters affect the energy range of accelerated particles.

Abstract

While the exact acceleration mechanism of energetic particles during solar flares is (as yet) unknown, magnetic reconnection plays a key role both in the release of stored magnetic energy of the solar corona and the magnetic restructuring during a flare. Recent work has shown that special field lines, called separators, are common sites of reconnection in 3D numerical experiments. To date, 3D separator reconnection sites have received little attention as particle accelerators. We investigate the effectiveness of separator reconnection as a particle acceleration mechanism for electrons and protons. We study the particle acceleration using a relativistic guiding-centre particle code in a time-dependent kinematic model of magnetic reconnection at a separator. The effect upon particle behaviour of initial position, pitch angle and initial kinetic energy are examined in detail, both for specific (single) particle examples and for large distributions of initial conditions. The separator reconnection model contains several free parameters and we study the effect of changing these parameters upon particle acceleration, in particular in view of the final particle energy ranges which agree with observed energy spectra.