Constraining inflationary magnetogenesis and reheating via GWs in light of PTA data

TL;DR

This paper uses PTA data to constrain models of inflationary magnetogenesis and reheating by analyzing gravitational wave contributions from primordial magnetic fields, providing new limits on early universe processes.

Contribution

It introduces a method to constrain reheating and magnetogenesis parameters using combined gravitational wave spectra from primordial magnetic fields and PTA observations.

Findings

Primordial magnetic fields can produce detectable GWs consistent with PTA data.

A broken power law describes the spectral energy density of primary and secondary GWs.

Blue spectra of PMFs with specific reheating scenarios fit PTA observations without new physics.

Abstract

By leveraging the limits on primordial magnetic fields (PMFs), their contributions to secondary gravitational waves (GWs), and the recent observations by the pulsar timing arrays (PTAs), we arrive at constraints on the epoch of reheating. We find that the combined spectral energy density of primary and secondary (generated by the PMFs) GWs can be described as a broken power law with different indices. We show that PMFs with blue spectra and appropriate reheating scenarios can successfully explain the PTA observations without invoking any new physics.