CMB and matter power spectra with non-linear dark-sector interactions

TL;DR

This paper explores a class of cosmological models with non-linear dark-sector interactions, analyzing their effects on cosmic microwave background and matter power spectra, and constraining them with Planck data.

Contribution

It introduces an analytically tractable model of dark matter and dark energy interaction and assesses its impact on structure formation and observational data.

Findings

Model reduces degeneracy in parameter space

Compatible with ΛCDM at 2σ confidence level

Slight preference for energy flow from dark matter to dark energy

Abstract

An interaction between dark matter and dark energy, proportional to the product of their energy densities, results in a scaling behavior of the ratio of these densities with respect to the scale factor of the Robertson-Walker metric. This gives rise to a class of cosmological models which deviate from the standard model in an analytically tractable way. In particular, it becomes possible to quantify the role of potential dark-energy perturbations. We investigate the impact of this interaction on the structure formation process. Using the (modified) CAMB code we obtain the CMB spectrum as well as the linear matter power spectrum. It is shown that the strong degeneracy in the parameter space present in the background analysis is considerably reduced by considering \textit{Planck} data. Our analysis is compatible with the $\Lambda$CDM model at the $2\sigma$ confidence level with a slightly preferred direction of the energy flow from dark matter to dark energy.