Particle Acceleration and Magnetic Dissipation in Relativistic Current Sheet of Pair Plasmas

TL;DR

This paper investigates relativistic current sheets in pair plasmas, demonstrating magnetic reconnection and drift kink instability, with implications for pulsar wind models, showing RDKI as a dominant dissipation mechanism.

Contribution

It provides the first detailed comparison of relativistic magnetic reconnection and drift kink instability in pair plasmas using particle-in-cell simulations.

Findings

Particles are strongly accelerated during reconnection.

Most magnetic energy converts into nonthermal plasma energy.

RDKI efficiently dissipates magnetic energy into plasma heat.

Abstract

We study linear and nonlinear development of relativistic and ultrarelativistic current sheets of pair plasmas with antiparallel magnetic fields. Two types of two-dimensional problems are investigated by particle-in-cell simulations. First, we present the development of relativistic magnetic reconnection, whose outflow speed is an order of the light speed c. It is demonstrated that particles are strongly accelerated in and around the reconnection region, and that most of magnetic energy is converted into "nonthermal" part of plasma kinetic energy. Second, we present another two-dimensional problem of a current sheet in a cross-field plane. In this case, the relativistic drift kink instability (RDKI) occurs. Particle acceleration also takes place, but the RDKI fast dissipates the magnetic energy into plasma heat. We discuss the mechanism of particle acceleration and the theory of the RDKI in detail. It is important that properties of these two processes are similar in the relativistic regime of T > mc^2, as long as we consider the kinetics. Comparison of the two processes indicates that magnetic dissipation by the RDKI is more favorable process in the relativistic current sheet. Therefore the striped pulsar wind scenario should be reconsidered by the RDKI.