Primordial gravitational waves: Model effects on time evolution and spectrum

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 ΛCDM. 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.