On the Origin of Cosmic Magnetic Fields

TL;DR

This paper reviews the origins of cosmic magnetic fields, discussing observational evidence, seed field generation, and amplification mechanisms like the alpha-omega dynamo, highlighting challenges in explaining their current strengths.

Contribution

It provides a comprehensive review of theories and observational data on cosmic magnetic field origins, emphasizing the limitations of the alpha-omega dynamo mechanism.

Findings

Seed magnetic fields likely originated before galaxy formation.

The alpha-omega dynamo faces difficulties due to flux conservation.

Observational evidence supports early magnetic fields in high redshift galaxies.

Abstract

We review the literature concerning how the cosmic magnetic fields pervading nearly all galaxies actually got started. some observational evidence involves the chemical abundance of the light elements Be and B, while another one is based on strong magnetic fields seen in high red shift galaxies. Seed fields, whose strength is of order 10^{-20} gauss, easily sprung up in the era preceding galaxy formation. Several mechanisms are proposed to amplify these seed fields to microgauss strengths. The standard mechanism is the Alpha-Omega dynamo theory. It has a major difficulty that makes unlikely to provide the sole origin. The difficulty is rooted in the fact that the total flux is constant. This implies that flux must be removed from the galactic discs. This requires that the field and flux be separated, for otherwise interstellar mass must be removed from the deep galactic gravitational and then their strength increased by the alpha omega theory.