Cosmic Alternator for the Onset of Large-Scale Magnetic Fields

TL;DR

This paper proposes a novel mechanism called the Cosmic Alternator that explains the generation of large-scale magnetic fields in collisionless plasmas through magnetic reconnection driven by anisotropic electron temperature fluctuations.

Contribution

It introduces a new process for magnetic field generation involving electron temperature anisotropy and reconnection, distinct from the Biermann Battery effect.

Findings

Magnetic fields can be generated in collisionless plasmas with inhomogeneous electron distributions.

The process involves magnetic reconnection driven by electron temperature anisotropy.

This mechanism differs from the Biermann Battery by requiring temperature anisotropy and reconnection.

Abstract

Magnetic field configurations extending over macroscopic scale distances are shown to be generated in rarefied collisionless plasmas when non-thermal and spatially inhomogeneous electron distributions in phase space emerge. The analyzed representative case is where, in the presence of a significant spatial gradient of the electron pressure and of a sheared magnetic field configuration, an alternating magnetic field reconnection process can develop associated with the anisotropy of the fluctuating electron temperature. The relevant process is intrinsically different from that known as the Biermann Battery which does not involve magnetic reconnection and requires that the unperturbed spatial gradient of the (isotropic) electron temperature be misaligned relative to that of the density gradient.