Electron Pre-Acceleration at Nonrelativistic High-Mach-Number Perpendicular Shocks

Abstract

We perform particle-in-cell simulations of perpendicular nonrelativistic collisionless shocks to study electron heating and pre-acceleration for parameters that permit extrapolation to the conditions at young supernova remnants. Our high-resolution large-scale numerical experiments sample a representative portion of the shock surface and demonstrate that the efficiency of electron injection is strongly modulated with the phase of the shock reformation. For plasmas with low and moderate temperature (plasma beta ${\beta }_{\mathrm{p}}=5\cdot 10^{-4}$ and ${\beta }_{\mathrm{p}}=0.5$), we explore the nonlinear shock structure and electron pre-acceleration for various orientations of the large-scale magnetic field with respect to the simulation plane while keeping it at $90^{\circ }$ to the shock normal. Ion reflection off the shock leads to the formation of magnetic filaments in the shock ramp, resulting from Weibel-type instabilities, and electrostatic Buneman modes in the shock foot. In all cases under study, the latter provides first-stage electron energization through the shock-surfing acceleration (SSA) mechanism. The subsequent energization strongly depends on the field orientation and proceeds through adiabatic or second-order Fermi acceleration processes for configurations with the out-of-plane and in-plane field components, respectively. For strictly out-of-plane field the fraction of supra-thermal electrons is much higher than for other configurations, because only in this case the Buneman modes are fully captured by the 2D simulation grid. Shocks in plasma with moderate ${\beta }_{\mathrm{p}}$ provide more efficient pre-acceleration. The relevance of our results to the physics of fully three-dimensional systems is discussed.

References in corpus (6)

• Primary particle acceleration above 100 TeV in the shell-type Supernova Remnant RX J1713.7-3946 with deep H.E.S.S. observations
• Production of Magnetic Turbulence by Cosmic Rays Drifting Upstream of Supernova Remnant Shocks
• Electron Shock Surfing Acceleration in Multidimensions: Two-dimensional Particle-In-Cell Simulation of Collisionless Perpendicular Shock
• Nonrelativistic collisionless shocks in weakly magnetized electron--ion plasmas: two-dimensional particle-in-cell simulation of perpendicular shock
• Two-dimensional full particle simulation of a perpendicular collisionless shock with a shock-rest-frame model
• Fundamentals of Non-relativistic Collisionless Shock Physics: V. Acceleration of Charged Particles

Cited by in corpus (5)

• Observations of Magnetic Reconnection in the Transition Region of Quasi-Parallel Shocks
• PIC Simulation Methods for Cosmic Radiation and Plasma Instabilities
• Kinetic simulations of nonrelativistic perpendicular shocks of young supernova remnants. I. Electron shock-surfing acceleration
• Non-thermal emission from the reverse shock of the youngest galactic Supernova remnant G1.9+0.3
• Stochastic re-acceleration and magnetic-field damping in Tycho's supernova remnant