Cosmological and lunar laser ranging constraints on evolving dark energy in a nonminimally coupled curvature-matter gravity model

TL;DR

This paper investigates a modified gravity model with nonminimal curvature-matter coupling, analyzing its cosmological implications and constraints from lunar laser ranging and DESI data, revealing a dynamical dark energy consistent with observations.

Contribution

It introduces a tracking solution in a nonminimally coupled gravity model and constrains its parameters using cosmological and lunar laser ranging data.

Findings

The model supports a dynamical dark energy compatible with recent DESI results.

Lunar laser ranging data constrains the model, ensuring consistency with equivalence principle tests.

A range of parameters produce a viable evolution of dark energy consistent with observations.

Abstract

We analyze a cosmological solution to the field equations of a modified gravity model where curvature and matter are nonminimally coupled. The current Universe's accelerated expansion is driven by a cosmological constant while the impact of the nonminimal coupling on the expansion history is recast as an effective equation of state for evolving dark energy. The model is analyzed under a tracking solution that follows the minimum of the effective potential for a scalar field that captures the modified theory's effects. We determine the conditions for the existence of this minimum and for the validity of the tracking solution. Cosmological constraints on the parameters of the model are obtained by resorting to recent outcomes of data from the DESI collaboration in combination with the Pantheon+ and Dark Energy Survey supernovae compilations, which give compatible results that point to the presence of a dynamical behavior for dark energy. The gravity model violates the equivalence principle since it gives rise to a fifth force that implies the Earth and Moon fall differently towards the Sun. The cosmological constraints are intersected with limits resulting from a test of the equivalence principle in the Earth-Moon system based on lunar laser ranging data. We find that a variety of model parameters are consistent with both of these constraints, all while producing a dynamical evolution of dark energy with similarities to that found in recent DESI results.