Pulsar timing array constraints on the cosmological magnetic field from quark confinement epoch

TL;DR

This paper uses pulsar timing array data and primordial black hole constraints to refine estimates of the cosmological magnetic field generated during the quark confinement epoch, suggesting a moderate first-order phase transition.

Contribution

It provides a novel combined analysis of PTA data and primordial black hole constraints to estimate the magnetic field parameters from the quark confinement epoch.

Findings

Magnetic field energy density near equipartition with photons.

Correlation length close to one co-moving parsec.

Consistent with a moderate strength first-order phase transition.

Abstract

Recent evidence for the stochastic gravitational wave backgorund reported by the pulsar timing arrays (PTA) can be interpreted as a signal from the cosmological phase transition. We use up-to-date models of the gravitational wave power spectra to compare constraints on the parameters of the phase transition for the three different available PTA measurements and to work out a refined estimate of the cosmological magnetic field that should result from this transition. We find that the PTA data, combined with a constraint from the abundance of primordial black holes, are consistent with a possibility of a moderate strength first-order phase transition during quark confinement and yield a rather precise prediction for the initial parameters of the magnetic field, with the magnetic field energy density in near equipartition with photon energy density and correlation length close to one co-moving parsec.