Dark Energy from Gauss-Bonnet and non-minimal couplings

TL;DR

This paper explores a scalar-tensor dark energy model with Gauss-Bonnet and non-minimal couplings, deriving exact solutions and reconstructing potentials to explain accelerated cosmic expansion consistent with observations.

Contribution

It introduces a new scalar-tensor dark energy model with exact solutions and a reconstruction method for potentials and couplings, covering various cosmological scenarios.

Findings

Exact solutions with equations of state matching observations

Reconstruction of scalar potential and Gauss-Bonnet coupling for different scenarios

Identification of conditions for accelerated expansion including quintessence and phantom

Abstract

We consider a scalar-tensor model of dark energy with Gauss-Bonnet and non-minimal couplings. Exact cosmological solutions were found in absence of potential, that give equations of state of dark energy consistent with current observational constraints, but with different asymptotic behaviors depending on the couplings of the model. A detailed reconstruction procedure is given for the scalar potential and the Gauss-Bonnet coupling for any given cosmological scenario. Particularly, we consider conditions for the existence of a variety of cosmological solutions with accelerated expansion, including quintessence, phantom, de Sitter, Little Rip. For the case of quintessence and phantom we have found a scalar potential of the Albrecht-Skordis type, where the potential is an exponential with a polynomial factor.