Constraints on Gauss-Bonnet Cosmologies

TL;DR

This paper reviews how modified Gauss-Bonnet gravity, motivated by string theory and scalar-tensor models, can address cosmological issues like singularities and late-time acceleration, and discusses observational constraints on these theories.

Contribution

It provides an overview of recent developments in constraining Gauss-Bonnet gravity theories using current cosmological and astrophysical data.

Findings

Gauss-Bonnet modifications admit nonsingular solutions.

They can explain matter-dark energy transition.

Constraints from recent observations limit these theories.

Abstract

The modified Gauss-Bonnet gravity can be motivated by a number of physical reasons, including: the uniqueness of a gravitational Lagrangian in four and higher dimensions and the leading order $\alpha^\prime$ corrections in superstring theory. Such an effective theory of scalar-tensor gravity has been modeled in the recent past to explain both the initial cosmological singularity problem and the observationally supported cosmological perturbations. Here I present an overview of the recent developments in the use of modified Gauss-Bonnet gravity to explain current observations, touching on key cosmological and astrophysical constraints applicable to theories of scalar-tensor gravity. The Gauss-Bonnet type modification of Einstein's theory admits nonsingular solutions for a wide range of scalar-curvature couplings. It also provides plausible explanation to some outstanding cosmological conundrums, including: the transition from matter dominance to dark energy and the late time cosmic acceleration. The focus is placed here to constrain such an effective theory of gravity against the recent cosmological and astrophysical observations.