The role of the Weibel instability at the reconnection jet front in relativistic pair plasma reconnection

TL;DR

This study uses particle-in-cell simulations to explore how the Weibel instability influences magnetic reconnection in relativistic pair plasmas, revealing its role in jet front propagation and current sheet expansion.

Contribution

It is the first investigation of the Weibel instability's role in large-scale magnetic reconnection in relativistic pair plasmas, combining microscopic and macroscopic perspectives.

Findings

Weibel instability generates electromagnetic fields comparable to piled-up fields.

The instability promotes rapid expansion of the current sheet.

Reconnection jet front propagates further due to the instability.

Abstract

The role of the Weibel instability is investigated for the first time in the context of the large-scale magnetic reconnection problem. A late-time evolution of magnetic reconnection in relativistic pair plasmas is demonstrated by particle-in-cell (PIC) simulations. In the outflow regions, powerful reconnection jet piles up the magnetic fields and then a tangential discontinuity appears there. Further downstream, it is found that the two-dimensional extension of the relativistic Weibel instability generates electro-magnetic fields, which are comparable to the anti-parallel or piled-up fields. In a microscopic viewpoint, the instability allows plasma's multiple interactions with the discontinuity. In a macroscopic viewpoint, the instability leads to rapid expansion of the current sheet and then the reconnection jet front further propagates into the downstream. Possible application to the three-dimensional case is briefly discussed.