Magnetic Fields from Heterotic Cosmic Strings

TL;DR

This paper proposes a mechanism where heterotic cosmic strings from M theory generate primordial seed magnetic fields, potentially explaining the origin of large-scale cosmic magnetism.

Contribution

It introduces a novel process involving heterotic cosmic strings from M5-branes to produce seed magnetic fields coherent on galactic scales.

Findings

Heterotic cosmic strings can generate seed magnetic fields.

The mechanism produces fields coherent on galactic scales.

Stable cosmic strings from M theory can influence cosmic magnetism.

Abstract

Large-scale magnetic fields are observed today to be coherent on galactic scales. While there exists an explanation for their amplification and their specific configuration in spiral galaxies -- the dynamo mechanism -- a satisfying explanation for the original seed fields required is still lacking. Cosmic strings are compelling candidates because of their scaling properties, which would guarantee the coherence on cosmological scales of any resultant magnetic fields at the time of galaxy formation. We present a mechanism for the production of primordial seed magnetic fields from heterotic cosmic strings arising from M theory. More specifically, we make use of heterotic cosmic strings stemming from M5--branes wrapped around four of the compact internal dimensions. These objects are stable on cosmological time scales and carry charged zero modes. Therefore a scaling solution of such defects will generate seed magnetic fields which are coherent on galactic scales today.