Hybrid Simulations of Particle Acceleration at Shocks

TL;DR

This paper presents large hybrid simulations studying particle acceleration at non-relativistic shocks, analyzing ion acceleration efficiency, magnetic field amplification, and turbulence effects, comparing results with diffusive shock acceleration theory.

Contribution

It provides detailed simulation results on ion acceleration and magnetic field amplification at shocks, highlighting the roles of shock inclination, strength, and instabilities, with implications for shock acceleration models.

Findings

Ion acceleration efficiency varies with shock parameters.

Magnetic field amplification is significant and correlates with turbulence.

Diffusion can be modeled as Bohm diffusion in amplified fields.

Abstract

We present the results of large hybrid (kinetic ions - fluid electrons) simulations of particle acceleration at non-relativistic collisionless shocks. Ion acceleration efficiency and magnetic field amplification are investigated in detail as a function of shock inclination and strength, and compared with predictions of diffusive shock acceleration theory, for shocks with Mach number up to 100. Moreover, we discuss the relative importance of resonant and Bell's instability in the shock precursor, and show that diffusion in the self-generated turbulence can be effectively parametrized as Bohm diffusion in the amplified magnetic field.