Stochastic gravitational waves backgrounds: a probe for inflationary and non-inflationary cosmology

TL;DR

This paper explores various physical scenarios that produce energetic stochastic gravitational wave backgrounds across a wide frequency range, highlighting cases with amplitudes vastly exceeding standard inflationary predictions and analyzing their spectral features.

Contribution

It introduces new scenarios for gravitational wave backgrounds with amplitudes much larger than inflationary models and discusses their spectral scaling violations.

Findings

Amplitudes can be up to eight orders of magnitude larger than inflationary predictions.

Spectral scaling violations provide signatures of different physical scenarios.

Wide frequency range of gravitational wave backgrounds analyzed.

Abstract

Physical scenarios, leading to highly energetic stochastic gravitational waves backgrounds (for frequencies ranging from the $\mu$Hz up to the GHz) are examined. In some cases the typical amplitude of the logarithmic energy spectrum can be even eight orders of magnitude larger than the ordinary inflationary prediction. Scaling violations in the frequency dependence of the energy density of the produced gravitons are discussed.