Interaction in the dark sector: a phenomenological approach

TL;DR

This paper investigates potential non-gravitational interactions between dark matter and dark energy by analyzing various parameterizations of dark matter density evolution using multiple cosmological data sets, finding no strong evidence against the standard model.

Contribution

It introduces a Bayesian framework to test phenomenological models of dark sector interactions without assuming a specific cosmological model.

Findings

Standard evolution law consistent within 2σ confidence level.

No strong evidence favoring interaction models over the standard model.

Weak or inconclusive Bayesian evidence for the tested interaction scenarios.

Abstract

The non-gravitational interaction between the dark components of the Universe could lead to the variation of dark matter energy density standard evolution law. When we assume this scenario, the dark matter energy density follows $\rho_{{dm}}\sim(1+z)^{3 + \epsilon(z)}$ (where $\epsilon(z)=0$ the standard law is recovered). In this paper, we perform a Bayesian analysis to test three parameterizations for $\epsilon(z)$, namely: $\epsilon(z)=\epsilon_0$, $\epsilon(z)=\epsilon_0 + \epsilon_1\frac{z}{1+z}$ and $\epsilon(z)=\epsilon_0 + \epsilon_1\frac{z(1+z)}{1+z^2}$, where the first one is motivated through the fundamental grounds and the others are on the phenomenological ones. Through the Gaussian process regression, our method uses galaxy cluster gas mass fraction measurements, SNe Ia observations, Cosmic Chronometers, and BAO data. No specific cosmological model is considered. In all possibilities analyzed, the standard evolution law ($\epsilon(z)=0$) is within $2\sigma$ c.l. The investigated cases generally indicated scenarios of inconclusive or weak evidence toward the simplest model from the Bayesian standpoint.