Particle acceleration by magnetic reconnection in geospace

TL;DR

This review summarizes recent advances in understanding how magnetic reconnection accelerates particles to high energies in Earth's magnetosphere, highlighting recent spacecraft observations and the need for further research on turbulence and energy partition.

Contribution

It provides a comprehensive overview of recent spacecraft studies on particle acceleration mechanisms during magnetic reconnection in Earth's magnetosphere.

Findings

Detailed observations of particle acceleration at various structures.

Discussion of the roles of electric fields, Fermi, and betatron effects.

Identification of gaps in understanding energy partition and turbulence effects.

Abstract

Particles are accelerated to very high, non-thermal energies during explosive energy-release phenomena in space, solar, and astrophysical plasma environments. While it has been established that magnetic reconnection plays an important role in the dynamics of Earth's magnetosphere, it remains unclear how magnetic reconnection can further explain particle acceleration to non-thermal energies. Here we review recent progress in our understanding of particle acceleration by magnetic reconnection in Earth's magnetosphere. With improved resolutions, recent spacecraft missions have enabled detailed studies of particle acceleration at various structures such as the diffusion region, separatrix, jets, magnetic islands (flux ropes), and dipolarization front. With the guiding-center approximation of particle motion, many studies have discussed the relative importance of the parallel electric field as well as the Fermi and betatron effects. However, in order to fully understand the particle acceleration mechanism and further compare with particle acceleration in solar and astrophysical plasma environments, there is a need for further investigation of, for example, energy partition and the precise role of turbulence.