Magnetic reconnection at the termination shock in a striped pulsar wind

TL;DR

This paper investigates the conditions under which magnetic energy is released through reconnection at the termination shock of a striped pulsar wind, combining analytical models with 1D PIC simulations.

Contribution

It derives a simple analytical criterion for magnetic reconnection at the termination shock and validates it with relativistic PIC simulations.

Findings

Reconnection occurs easily at relativistic, highly magnetized shocks.

A simple criterion predicts when magnetic dissipation happens.

Simulations confirm the analytical condition.

Abstract

Most of the rotational luminosity of a pulsar is carried away by a relativistic magnetised wind in which the matter energy flux is negligible compared to the Poynting flux. Near the equatorial plane of an obliquely rotating pulsar magnetosphere, the magnetic field reverses polarity with the pulsar period, forming a wind with oppositely directed field lines. This structure is called a striped wind; dissipation of alternating fields in the striped wind is the object of our study. The aim of this paper is to study the conditions required for magnetic energy release at the termination shock of the striped pulsar wind. Magnetic reconnection is considered via analytical methods and 1D relativistic PIC simulations. An analytical condition on the upstream parameters for partial and full magnetic reconnection is derived from the conservation laws of energy, momentum and particle number density across the relativistic shock. Furthermore, by using a 1D relativistic PIC code, we study in detail the reconnection process at the termination shock. We found a very simple criterion for dissipation of alternating fields at the termination shock, depending on the upstream parameters of the flow. 1D relativistic PIC simulations are in agreement with our criterion. Thus, alternating magnetic fields annihilate easily at relativistic highly magnetised shocks.