Models of coupled dark matter to dark energy

TL;DR

This paper introduces three novel models of dark energy as scalar fields coupled to dark matter, analyzing their cosmological implications through background and perturbation studies, and computing observable spectra.

Contribution

It generalizes fluid actions to include scalar field couplings and explores their effects on cosmological observables.

Findings

Different models produce distinct CMB and matter power spectra.

Couplings influence the evolution of dark energy and dark matter.

Models provide new frameworks for understanding dark sector interactions.

Abstract

We present three distinct types of models of dark energy in the form of a scalar field which is explicitly coupled to dark matter. Our construction draws from the pull-back formalism for fluids and generalises the fluid action to involve couplings to the scalar field. We investigate the cosmology of each class of model both at the background and linearly perturbed level. We choose a potential for the scalar field and a specific coupling function for each class of models and we compute the Cosmic Microwave Background and matter power spectra.