f(G) modified gravity and the energy conditions

TL;DR

This paper explores the viability of modified Gauss-Bonnet gravity theories, focusing on energy conditions and their implications for cosmic acceleration and avoiding future singularities.

Contribution

It analyzes a specific f(G) model motivated by string theory that addresses late-time acceleration and singularity issues, assessing its viability through energy conditions.

Findings

The f(G) model can satisfy energy conditions under certain bounds.

The model explains late-time cosmic acceleration.

It potentially cures finite-time future singularities.

Abstract

Motivated by string/M-theory predictions that scalar field couplings with the Gauss-Bonnet invariant, G, are essential in the appearance of non-singular early time cosmologies, we discuss the viability of an interesting alternative gravitational theory, namely, modified Gauss-Bonnet gravity, and present the viability bounds arising from the energy conditions. In particular, we consider a specific realistic form of f(G) analyzed in the literature that accounts for the late-time cosmic acceleration and that has been found to cure the finite-time future singularities present in the dark energy models, and further examine the respective viability of the specific f(G) model imposed by the weak energy condition.