The dark sector of the Universe as a scalar field in Horndeski Gravity

Abstract

In the present work, we study a subclass of Horndeski gravity characterized by a non-minimal derivative coupling between a scalar field and the Einstein tensor, as a possible alternative to alleviate the observational tension associated with estimates of the Hubble constant $H_{0}$. Two scenarios within a flat FRW spacetime were considered. In the first case, the scalar field mimics cold dark matter, whereas in the second case, it acts as dark energy. We derive the dynamical equations and perform a statistical analysis using observational data of $H(z)$, obtaining constraints for the cosmological parameters. The results indicate that the model can effectively fit the cosmic expansion rate at late epochs, providing values of $H_{0}$ that are more compatible with local measurements. These results suggest that the non-minimal coupling sector in the Horndeski context constitutes a viable and promising approach to alleviate the $H_{0}$ tension and investigate scenarios beyond the standard cosmological model.