Particle Acceleration by Magnetic Reconnection

TL;DR

This paper explores how magnetic reconnection acts as an efficient particle acceleration mechanism in astrophysical environments, complementing other known processes like shocks and turbulence.

Contribution

It provides a detailed discussion of particle acceleration within magnetic reconnection sites, highlighting first and second order Fermi processes in different conditions.

Findings

Particles can be accelerated efficiently via reconnection in large scale current sheets.

Local turbulence enhances reconnection speed and acceleration efficiency.

Reconnection-driven acceleration operates alongside other mechanisms in astrophysical settings.

Abstract

Observational data require a rich variety of mechanisms to accelerate fast particles in astrophysical environments operating under different conditions. The mechanisms discussed in the literature include varying magnetic fields in compact sources, stochastic processes in turbulent environments, and acceleration behind shocks. An alternative, much less explored mechanism involves particle acceleration within magnetic reconnection sites. In this chapter we discuss this mechanism and show that particles can be efficiently accelerated by reconnection through a first order Fermi process within large scale current sheets (specially when in the presence of local turbulence which speeds up the reconnection and make the acceleration region thicker) and also through a second order Fermi process in pure MHD turbulent environments.