Is inflationary magnetogenesis sensitive to the post-inflationary history ?

TL;DR

This paper demonstrates that the large-scale primordial magnetic field spectrum generated during inflation remains unaffected by the universe's post-inflationary evolution, including variations in the barotropic parameter and gauge couplings.

Contribution

It reveals that the spectral shape of inflationary magnetogenesis is insensitive to post-inflationary history, contrary to previous assumptions.

Findings

Magnetic field spectrum shape is unaffected by post-inflationary parameters.

Post-inflationary evolution does not alter the primordial magnetic spectrum.

Insensitivity holds for various barotropic parameters and gauge couplings.

Abstract

Considering inflationary magnetogenesis induced by time-dependent kinetic and axial couplings of a massless Abelian vector boson field breaking the conformal invariance we show in this article that, surprisingly, the spectral shape of the large-scale primordial magnetic field power spectrum is insensitive to the post-inflationary history, namely the barotropic parameter ($w$) and the gauge coupling functions of the post-inflationary era.