Biermann battery-mediated magnetic reconnection in 3-D colliding plasmas

TL;DR

This paper uses 3-D kinetic simulations to explore a novel, fast magnetic reconnection mechanism driven by the Biermann battery effect in colliding plasmas, relevant to astrophysical phenomena.

Contribution

It reveals a new 3-D reconnection process mediated by Biermann battery effects, combining temperature and density profiles, with implications for astrophysical plasma dynamics.

Findings

Identification of a fast, localized Biermann-mediated reconnection process.

Demonstration of the role of electron pressure tensor and plasmoids in reconnection.

Development of a general formulation for astrophysical relevance.

Abstract

Recent experiments have demonstrated magnetic reconnection between colliding plasma plumes, where the reconnecting magnetic fields were self-generated in the plasma by the Biermann battery effect. Using fully kinetic 3-D simulations, we show the full evolution of the magnetic fields and plasma in these experiments including self-consistent magnetic field generation about the expanding plume. The collision of the two plasmas drives the formation of a current sheet, where reconnection occurs in a strongly time-and space-dependent manner, demonstrating a new 3-D reconnection mechanism. Specifically, we observe fast, vertically-localized Biermann-mediated reconnection, an inherently 3-D process where the temperature profile in the current sheet coupled with the out-of-plane ablation density profile conspires to break inflowing field lines, reconnecting the field downstream. Fast reconnection is sustained by both the Biermann effect and the traceless electron pressure tensor, where the development of plasmoids appears to modulate the contribution of the latter. We present a simple and general formulation to consider the relevance of Biermann-mediated reconnection in general astrophysical scenarios.