Magnetogenesis in Cyclical Universe

TL;DR

This paper presents a cyclic cosmology model where magnetic fields are generated during the contracting phase, avoiding issues of inflationary magnetogenesis and not requiring new physics or specific modified gravity theories.

Contribution

It introduces a simple, general cyclic universe model for magnetogenesis that does not rely on additional scalar fields or non-minimal couplings, and avoids backreaction problems.

Findings

Magnetic fields of observationally relevant strength can be generated during contraction.

The model does not require new physics or specific modified gravity theories.

It avoids backreaction and strong coupling issues common in inflationary magnetogenesis.

Abstract

We propose a simple solution to the magnetogenesis problem based on cyclic cosmology. It is demonstrated that magnetic fields, of sufficient strengths to account for the present observational bounds, can be created in the contracting phase preceding the beginning of the current cosmological cycle. The basic assumption of this model is that the Universe enters a contraction phase essentially empty, characterized by small seed electric fields. In this framework, there is no need for any new theoretical additions to explain magnetogenesis, such as new scalar fields or non-minimal couplings between curvature, scalar fields and the electromagnetic sector. Moreover, the proposed model is general in the sense that it does not assume any specific modified gravity theory to enable the cosmological bounce. When compared to the inflationary magnetogenesis paradigm, the proposed model also has the advantage of not leading to the backreaction and strong coupling problems.