Magnetogenesis in Matter - Ekpyrotic Bouncing Cosmology

TL;DR

This paper proposes a nonsingular bouncing cosmology model that successfully generates primordial magnetic fields, overcoming previous issues faced by inflationary models, and aligns with observational data without instabilities.

Contribution

It introduces a novel bouncing cosmology framework for magnetogenesis that avoids back reaction and strong coupling problems, producing scale-invariant spectra consistent with observations.

Findings

Supports magnetogenesis in bouncing cosmology avoiding known problems.

Achieves a scale-invariant magnetic power spectrum compatible with CMB data.

No BKL instability occurs within the model's parameter range.

Abstract

In the recent past there have been many attempts to associate the generation of primordial magnetic seed fields with the inflationary era, but with limited success. We thus take a different approach by using a model for nonsingular bouncing cosmology. A coupling of the electromagnetic Lagrangian $F_{\mu\nu}F^{\mu\nu}$ with a non background scalar field has been considered for the breaking of conformal invariance. We have shown that non singular bouncing cosmology supports magnetogenesis evading the long standing back reaction and strong coupling problems which have plagued inflationary magnetogenesis. In this model, we have achieved a scale invariant power spectrum for the parameter range compatible with observed CMB anisotropies. The desired strength of the magnetic field has also been obtained that goes in accordance with present observations. It is also important to note that no BKL instability arises within this parameter range. The energy scales for different stages of evolution of the bouncing model are so chosen that they solve the problems of Standard Big Bang cosmology as well.