Electron acceleration in supernova remnants

Abstract

Supernova remnants (SNRs) are believed to produce the majority of galactic cosmic rays (CRs). SNRs harbor non-relativistic collisionless shocks responsible for the acceleration of CRs via diffusive shock acceleration (DSA), in which particles gain their energy via repeated interactions with the shock front. Since the DSA theory involves pre-existing mildly energetic particles, a means of pre-acceleration is required, especially for electrons. Electron injection remains one of the most troublesome and still unresolved issues and our physical understanding of it is essential to fully comprehend the physics of SNRs. To study any electron-scale phenomena responsible for pre-acceleration, we require a method capable of resolving these small kinetic scales and particle-in-cell simulations that fulfill this criterion. Here, I report on the latest achievements made by utilizing kinetic simulations of non-relativistic high Mach number shocks. I discuss how the physics of SNR shocks depends on the shock parameters (e.g. the shock obliquity, Mach number, the ion-to-electron mass ratio) as well as the processes responsible for the electron heating and acceleration.