Testing viable extensions of Einstein-Gauss-Bonnet gravity

TL;DR

This paper explores extended Einstein-Gauss-Bonnet gravity models with a scalar field, demonstrating they fit cosmological data well and may outperform the standard Lambda-CDM model.

Contribution

It introduces a viable extension of Einstein-Gauss-Bonnet gravity with a scalar field that maintains correct gravitational wave speed and fits observational data effectively.

Findings

Models fit observational data well

Theories provide stable cosmological evolution

Some parameters outperform Lambda-CDM fits

Abstract

Some models within the framework of Gauss-Bonnet gravities are considered in the presence of a non-minimally coupled scalar field. By imposing a particular constraint on the scalar field coupling, an extension of the called Einstein-Gauss-Bonnet gravity that keeps the correct speed of propagation for gravitational waves, is considered. The cosmological evolution for this viable class of models is studied and compared with observational data (BAO, CMB, Sne Ia,..), where we obtain the corresponding bounds for these theories and show that such theories fit well the data and provide a well-behaved cosmological evolution in comparison to the standard model of cosmology. Some statistical parameters show that the goodness of the fits are slightly better than those for $\Lambda$CDM model.