Effects of Multiscale Plasma Waves on Electron Preacceleration at Weak Quasi-perpendicular Intracluster Shocks

Abstract

Radio relics associated with merging galaxy clusters indicate the acceleration of relativistic electrons in merger-driven shocks with low sonic Mach numbers (M (s) less than or similar to 3) in the intracluster medium (ICM). Recent studies have suggested that electron injection to diffusive shock acceleration (DSA) could take place through the so-called Fermi-like acceleration in the shock foot of beta = P (gas)/P (B) approximate to 20-100 shocks and the stochastic shock drift acceleration (SSDA) in the shock transition of beta approximate to 1-5 shocks. Here, we explore how the SSDA can facilitate electron preacceleration in weak quasi-perpendicular (Q (perpendicular to)) shocks in beta approximate to 20-100 plasmas by performing particle-in-cell simulations in a two-dimensional domain large enough to properly encompass ion-scale waves. We find that in supercritical shocks with Ms greater than or similar to MAIC*similar to 2.3