Gravitational waves from the evolution of magnetic field after electroweak epoch

TL;DR

This paper investigates how the evolution of primordial magnetic fields influenced by chiral quantum anomaly can generate gravitational waves during the electroweak epoch, potentially detectable today and affecting cosmological processes.

Contribution

It introduces a model linking chiral magnetic field evolution with gravitational wave production in the early universe, providing estimates for observable effects.

Findings

Threshold initial chiral asymmetry for detectable gravitational waves

Gravitational waves from magnetic field evolution could impact big-bang nucleosynthesis

Potential observability of primordial gravitational waves in current and future detectors

Abstract

It was recently demonstrated that the evolution of helical magnetic field in the primordial plasma at temperatures $T\gtrsim10$ MeV is affected by the phenomenon of chiral quantum anomaly in the electroweak model, leading to a possibility of self-sustained existence of magnetic field and chiral asymmetry in the electronic distribution. This may serve as a mechanism for generating primordial magnetic field in the early universe. Violent magnetic-field generation may lead to production of gravitational waves which, regardless of the fate of magnetic field itself, survive until today. We estimate the threshold value of the initial chiral asymmetry above which the generated gravitational waves would affect the big-bang nucleosynthesis and would show up in the current and future experiments on gravitational-wave detection.