Mildly relativistic magnetized shocks in electron-ion plasmas I. Electromagnetic shock structure

TL;DR

This study uses high-resolution 2D particle-in-cell simulations to explore the structure and electromagnetic phenomena of mildly relativistic, magnetized electron-ion shocks, revealing ion-scale effects, wave amplification, and upstream plasma interactions.

Contribution

It provides new insights into shock surface corrugations, wave generation, and electromagnetic emission mechanisms in mildly relativistic electron-ion shocks, supported by large-scale kinetic simulations.

Findings

Ion-scale corrugations depend on magnetic field orientation.

Synchrotron maser instability persists in these shocks.

Wave amplification and upstream electrostatic wakefields are observed.

Abstract

Mildly relativistic shocks in magnetized electron-ion plasmas are investigated with 2D kinetic particle-in-cell simulations of unprecedentedly high resolution and large scale for conditions that may be found at internal shocks in blazar cores. Ion-scale effects cause corrugations along the shock surface whose properties somewhat depend on the configuration of the mean perpendicular magnetic field, that is either in or out of the simulation plane. We show that the synchrotron maser instability persists to operate in mildly relativistic shocks in agreement with theoretical predictions and produces coherent emission of upstream-propagating electromagnetic waves. Shock front ripples are excited in both mean-field configurations and they engender effective wave amplification. The interaction of these waves with upstream plasma generates electrostatic wakefields.