Simple parametrisation for coupled dark energy

TL;DR

This paper introduces a simple, flexible parametrisation for coupled dark energy involving a scalar field and dark matter interaction, constrained by Planck and KiDS data, revealing differences between early and late universe observations.

Contribution

It presents a new, minimal phenomenological model for coupled dark energy that extends standard parametrisations and is constrained by recent cosmological data.

Findings

The model captures diverse dark energy evolutions at low redshift.

Constraints from Planck and KiDS data show differences between early and late universe.

The parametrisation complements existing CPL models.

Abstract

We propose a phenomenological generalisation of the standard model with only one extra degree of freedom that parametrises the evolution of a scalar field responsible for the cosmic acceleration. The model also foresees an additional parameter in the form of a coupling between dark energy and dark matter. This model captures a large diversity of dark energy evolutions at low redshift and could usefully complement common CPL parametrisations widely used. In this context, we have been constraining the parametrisation with data from Planck and KiDS, bringing different results between the early and late universe observations.