Primordial gravitational waves: Model effects on time evolution and spectrum

TL;DR

This paper studies the evolution and spectrum of primordial gravitational waves generated during inflation, highlighting how different dark energy models and interactions influence their characteristics and potential for constraining cosmological theories.

Contribution

It analyzes the impact of various dark energy models, including interactions, on primordial gravitational wave spectra within a standard inflationary framework.

Findings

Spectrum varies significantly with cosmological model.

Dark energy-dark matter interaction leaves a detectable imprint.

Primordial GWs can constrain dark energy models.

Abstract

With the detection of gravitational waves (GW) in recent years, many papers that use simulated GW datasets to constrain dark energy models have been published. However, these works generally consider GW generated by massive astrophysical objects, such as mergers of black holes or neutron stars. In this paper, we analyse the evolution and spectrum of GW generated in the inflationary epoch, assuming a standard slow-roll single-field inflationary scenario. Three models for the background are considered: a field theory model of interacting dark energy - the Interacting Holographic Tachyonic Model, the Holographic Dark Energy Model, and the {\Lambda}CDM. The results show significant dependence on the cosmological model, especially for the spectrum, and in particular show that an interaction between dark energy and dark matter can leave a significant imprint. Therefore, future primordial gravitational waves (PGW) datasets could be very useful for constraining dark energy models, including to probe an interaction in the dark sector of the universe.