Unification of inflation, dark energy, and dark matter within the Salam-Sezgin cosmological model

TL;DR

This paper extends a Salam-Sezgin supergravity cosmological model to include an inflationary period, aiming to unify inflation, dark matter, and dark energy, and analyzes its gravitational-wave spectrum.

Contribution

It demonstrates a method to incorporate warm inflation into the Salam-Sezgin model, unifying key cosmological phenomena within a supergravity framework.

Findings

The model's gravitational-wave spectrum has a negative slope in the 10^(-15)-10^6 rad/s range.

The spectrum shows no structure in the MHz/GHz frequency range.

Partial success in modeling dark matter content from scalar fields.

Abstract

We investigate a cosmological model, based on the Salam-Sezgin six-dimensional supergravity theory and on previous work by Anchordoqui, Goldberg, Nawata, and Nu\~nez. Assuming a period of warm inflation, we show that it is possible to extend the evolution of the model back in time, to include the inflationary period, thus unifying inflation, dark matter, and dark energy within a single framework. Like the previous authors, we were not able to obtain the full dark matter content of the Universe from the Salam-Sezgin scalar fields. However, even if only partially successful, this work shows that present-day theories, based on superstrings and supergravity, may eventually lead to a comprehensive modelling of the evolution of the Universe. We find that the gravitational-wave spectrum of the model has a non-constant negative slope in the frequency range 10^(-15)-10^6 rad/s, and that, unlike standard (cold) inflation models, it shows no structure in the MHz/GHz range of frequencies.