Particle Acceleration by Magnetic Reconnection in AGNs and in the IGM

TL;DR

This paper investigates particle acceleration via magnetic reconnection in AGNs, demonstrating efficient energy growth through a Fermi process, and discusses cosmic ray propagation in the collisionless intergalactic medium.

Contribution

It introduces magnetic reconnection as a significant acceleration mechanism in AGNs and explores its implications for cosmic ray propagation in the IGM.

Findings

Particles are efficiently accelerated through a first-order Fermi process in magnetic reconnection sites.

Energy of particles grows exponentially during acceleration.

Kinetic effects influence cosmic ray propagation in the collisionless IGM.

Abstract

There is no single mechanism by which fast particles are accelerated in astrophysical environments, and it is now recognized that the data require a rich variety of different mechanisms 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 so far, involves particle acceleration within magnetic reconnection sites. In this work, we explore this mechanism in the AGN framework and show that particles are efficiently accelerated through a first-order Fermi process and have an exponential growth of energy. We also address briefly the propagation of cosmic rays (CRs) in the intergalactic medium (IGM). Since the latter is a collisionless environment, kinetic effects must be considered which will affect the turbulent magnetic field distribution and therefore, the CR propagation.