Particle Acceleration in Kink-unstable Jets

Abstract

Magnetized jets in gamma-ray bursts and active galactic nuclei are thought to be efficient accelerators of particles; however, the process responsible for the acceleration is still a matter of active debate. In this work, we study the kink instability in non-rotating force-free jets using first-principle particle-in-cell simulations. We obtain similar overall evolution of the instability as found in magnetohydrodynamics simulations. The instability first generates large-scale current sheets, which at later times break up into small-scale turbulence. Reconnection in these sheets proceeds in the strong guide field regime, which results in a formation of steep power laws in the particle spectra. Later evolution shows heating of the plasma, which is driven by small-amplitude turbulence induced by the kink instability. These two processes energize particles due to a combination of ideal and non-ideal electric fields.