Cosmological Magnetic Fields: Their Generation, Evolution and Observation

TL;DR

This paper reviews mechanisms for generating cosmological magnetic fields, their evolution, and how they can be observed through radio, gamma-ray, and cosmic ray astronomy, emphasizing their testability and open questions.

Contribution

It provides a comprehensive review of magnetogenesis scenarios, their evolution, and discusses observational prospects and challenges in testing primordial magnetic fields.

Findings

Primordial magnetic fields are observationally testable.

Magnetic fields in the intergalactic medium have specific strength and correlation length ranges.

Future observations can address key open questions in cosmological magnetism.

Abstract

We review the possible mechanisms for the generation of cosmological magnetic fields, discuss their evolution in an expanding Universe filled with the cosmic plasma and provide a critical review of the literature on the subject. We put special emphasis on the prospects for observational tests of the proposed cosmological magnetogenesis scenarios using radio and gamma-ray astronomy and ultra high energy cosmic rays. We argue that primordial magnetic fields are observationally testable. They lead to magnetic fields in the intergalactic medium with magnetic field strength and correlation length in a well defined range. We also state the unsolved questions in this fascinating open problem of cosmology and propose future observations to address them.