Graviton Production by a Thermal Bath

TL;DR

This paper investigates gravitational wave production from thermal fluctuations in the early universe and hot astrophysical objects using finite temperature field theory, revealing notable deviations from the expected spectrum.

Contribution

It introduces a field theory approach to analyze gravitational wave spectra from thermal sources, focusing on the infrared region with dissipative effects.

Findings

Significant deviations from a Planck spectrum in GW production

Infrared region dominated by dissipative effects

Enhanced detectability prospects for thermal GW signals

Abstract

Thermal fluctuations in the early universe plasma and in very hot astrophysical objects are an unavoidable source of gravitational waves (GW). Differently from previous studies on the subject, we approach this problem using methods based on field theory at finite temperature. Such an approach allows to probe the infrared region of the spectrum where dissipative effects are dominant. Incidentally, this region is the most interesting from the point of view of the detectability perspectives. We find significant deviations from a Planck spectrum.