Cyclotron resonant interactions in cosmic particle accelerators

TL;DR

This paper reviews cyclotron resonant interactions in space plasmas, highlighting various resonance types and recent topics like electron injection, ion heating, and relativistic effects, providing a comprehensive overview of their roles in cosmic particle acceleration.

Contribution

It introduces a simple formulation for test particle interactions and discusses multiple resonance mechanisms, expanding understanding of their significance in space plasma phenomena.

Findings

Multiple resonance types can occur in oblique whistler wave interactions.

Resonant interactions influence electron injection and ion heating in space plasmas.

Recent studies include relativistic effects and their impact on particle acceleration.

Abstract

A review is given for cyclotron resonant interactions in space plasmas. After giving a simple formulation for the test particle approach, illustrative examples for resonant interactions are given. It is shown that for obliquely propagating whistler waves, not only fundamental cyclotron resonance, but also other resonances, such as transit-time resonance, anomalous cyclotron resonance, higher-harmonic cyclotron resonance, and even subharmonic resonance can come into play. A few recent topics of cyclotron resonant interactions, such as electron injection in shocks, cyclotron resonant heating of solar wind heavy ions, and relativistic modifications, are also reviewed.