Towards inflation and dark energy cosmologies from modified Gauss-Bonnet theory

TL;DR

This paper proposes a modified Gauss-Bonnet gravity model with a scalar field that explains early universe inflation and late-time acceleration, matching observational data and providing a reheating mechanism.

Contribution

It introduces a novel cosmological model with field-dependent Gauss-Bonnet coupling, demonstrating its ability to produce inflation, dark energy effects, and consistent perturbation spectra.

Findings

Model predicts inflationary spectra within experimental bounds

Provides a reheating mechanism similar to friction-based models

Explains late-time cosmic acceleration

Abstract

We consider a physically viable cosmological model that has a field dependent Gauss-Bonnet coupling in its effective action, in addition to a standard scalar field potential. The presence of such terms in the four dimensional effective action gives rise to several novel effects, such as a four dimensional flat Friedmann-Robertson-Walker universe undergoing a cosmic inflation at early epoch, as well as a cosmic acceleration at late times. The model predicts, during inflation, spectra of both density perturbations and gravitational waves that may fall well within the experimental bounds. Furthermore, this model provides a mechanism for reheating of the early universe, which is similar to a model with some friction terms added to the equation of motion of the scalar field, which can imitate energy transfer from the scalar field to matter