Primordial magnetic fields and nonlinear electrodynamics

TL;DR

This paper investigates how nonlinear electrodynamics during inflation can generate large-scale primordial magnetic fields, which become linear after inflation, potentially explaining observed cosmic magnetic fields.

Contribution

It introduces a model where nonlinear electrodynamics during inflation produces primordial magnetic fields with viable strengths, a novel approach to cosmic magnetogenesis.

Findings

Primordial magnetic fields of cosmologically interesting strength can be generated.

Nonlinear electrodynamics with power-law Lagrangians is effective during inflation.

Magnetic field generation ceases as electrodynamics becomes linear after inflation.

Abstract

The creation of large scale magnetic fields is studied in an inflationary universe where electrodynamics is assumed to be nonlinear. After inflation ends electrodynamics becomes linear and thus the description of reheating and the subsequent radiation dominated stage are unaltered. The nonlinear regime of electrodynamics is described by lagrangians having a power law dependence on one of the invariants of the electromagnetic field. It is found that there is a range of parameters for which primordial magnetic fields of cosmologically interesting strengths can be created.