Biermann Battery Powered by Resistive Heating Induced by Cosmic Ray Streaming

TL;DR

This paper introduces a new cosmic ray-driven Biermann battery mechanism that generates seed magnetic fields during early universe structure formation, potentially explaining the origin of galactic magnetic fields.

Contribution

It proposes a novel magnetic field generation process driven by cosmic ray streaming-induced resistive heating, dominant in specific early universe conditions.

Findings

Mechanism effective in small-scale, low-temperature, highly-ionized regions.

Produces seed magnetic fields strong enough for galactic dynamo amplification.

Operates during the epoch of structure formation after first star death.

Abstract

It is recently proposed that cosmic rays generate a seed magnetic field in the early universe. In this paper, we propose another generation mechanism of magnetic fields by cosmic rays, which is the Biermann battery driven by resistive heating induced by the streaming of cosmic rays. This mechanism is dominant in small-scale, low-temperature, and strongly-ionized regions, compared with other previously proposed mechanisms. Because cosmic rays are expected to be accelerated after the death of the first stars, this mechanism can work during structure formation in the early universe. We show that it makes the seed magnetic field with sufficient strength for the subsequent dynamo to amplify it to the micro Gauss level in the current galaxies.