Relic Gravitational Waves from the Chiral Plasma Instability in the Standard Cosmological Model

TL;DR

This paper explores how chiral plasma instability in the early universe's primordial plasma, based solely on Standard Model physics, can produce detectable relic magnetic fields and gravitational waves observable today.

Contribution

It demonstrates that relic gravitational waves and magnetic fields originate from chiral asymmetries in the Standard Model, with estimates validated by 3D numerical simulations.

Findings

Relic magnetic field spectrum estimated.

Gravitational wave background spectrum estimated.

Validation through 3D numerical simulations.

Abstract

In the primordial plasma, at temperatures above the scale of electroweak symmetry breaking, the presence of chiral asymmetries is expected to induce the development of helical hypermagnetic fields through the phenomenon of chiral plasma instability. It results in magnetohydrodynamic turbulence due to the high conductivity and low viscosity and sources gravitational waves that survive in the universe today as a stochastic polarized gravitational wave background. In this article, we show that this scenario only relies on Standard Model physics, and therefore the observable signatures, namely the relic magnetic field and gravitational background, are linked to a single parameter controlling the initial chiral asymmetry. We estimate the magnetic field and gravitational wave spectra, and validate these estimates with 3D numerical simulations.