Magnetic field evolution in relativistic unmagnetized collisionless shocks

TL;DR

This study uses large-scale 2D particle-in-cell simulations to investigate how magnetic fields evolve in relativistic unmagnetized collisionless shocks, revealing the growth of magnetic fields and particle acceleration effects.

Contribution

It provides new insights into magnetic field amplification and particle acceleration in relativistic shocks using unprecedented simulation scales.

Findings

Magnetic fields grow on larger scales over time.

Shock-accelerated particles carry over 10% of energy flux.

Magnetic fields and particles influence astrophysical flow magnetization limits.

Abstract

We study relativistic unmagnetized collisionless shocks using unprecedentedly large particle-in-cell simulations of two-dimensional pair plasma. High energy particles accelerated by the shock are found to drive magnetic field evolution on a timescale >10^4 plasma times. Progressively stronger magnetic fields are generated on larger scales in a growing region around the shock. Shock-generated magnetic fields and accelerated particles carry >1% and >10% of the downstream energy flux, respectively. Our results suggest limits on the magnetization of relativistic astrophysical flows.