Testing coupled dark energy models with their cosmological background evolution

TL;DR

This paper investigates a cosmological model where dark matter interacts with a scalar field responsible for cosmic acceleration, using observational data to constrain conformal and disformal couplings, and finds disformal interactions are favored over standard models.

Contribution

It introduces a combined analysis of conformal and disformal couplings in dark energy models and demonstrates that disformal interactions are preferred at the background level based on observational data.

Findings

Disformal coupling relaxes conformal coupling constraints.

Disformal interaction is preferred over ΛCDM and uncoupled quintessence.

Interacting dark energy models are favored by background evolution data.

Abstract

We consider a cosmology in which dark matter and a quintessence scalar field responsible for the acceleration of the Universe are allowed to interact. Allowing for both conformal and disformal couplings, we perform a global analysis of the constraints on our model using Hubble parameter measurements, baryon acoustic oscillation distance measurements, and a Supernovae Type Ia data set. We find that the additional disformal coupling relaxes the conformal coupling constraints. Moreover we show that, at the background level, a disformal interaction within the dark sector is preferred to both $\Lambda$CDM and uncoupled quintessence, hence favouring interacting dark energy.