Particle Injection Problem in Magnetic Reconnection and Turbulence

TL;DR

This paper reviews recent progress in understanding how particles are initially energized in magnetic reconnection and turbulence, which is crucial for explaining high-energy cosmic phenomena.

Contribution

It provides a comprehensive overview of current models and mechanisms of particle injection in magnetic reconnection and turbulence environments.

Findings

Identification of key injection mechanisms in reconnection and turbulence

Insights into how injection influences nonthermal particle populations

Discussion of future research directions in particle acceleration

Abstract

Magnetic reconnection and turbulence in magnetically-dominated environments have been proposed as important nonthermal particle acceleration mechanisms that generate high energy particles and associated emissions. While the acceleration to high energy that produces the power-law energy distribution has drawn strong interest, recent studies actively discuss pre-acceleration, or injection, to a sufficient energy for a sustained and prolonged Fermi-like acceleration. The injection process is important for determining the fraction of nonthermal particles and energy partition between thermal and nonthermal particles. We review recent advances in understanding the injection mechanisms responsible for populating these nonthermal power-law spectra, and conclude with an outlook for studies and applications of injection models.