On the Dark Sector Interactions

TL;DR

This paper investigates dark energy and dark matter interactions using observational data, revealing that the interaction term likely crosses zero and oscillates, indicating the need for more general models.

Contribution

It introduces a model-independent method to analyze dark sector interactions by dividing redshift into bins and fitting a constant interaction term in each, revealing oscillatory behavior.

Findings

Interaction term likely crosses zero

Interaction exhibits oscillatory behavior

More general models are needed for dark sector interactions

Abstract

It is possible that there exist some interactions between dark energy (DE) and dark matter (DM), and a suitable interaction can alleviate the coincidence problem. Several phenomenological interacting forms are proposed and are fitted with observations in the literature. In this paper we investigate the possible interaction in a way independent of specific interacting forms by use of observational data (SNe, BAO, CMB and Hubble parameter). We divide the whole range of redshift into a few bins and set the interacting term $\delta(z)$ to be a constant in each redshift bin. We consider four parameterizations of the equation of state $w_{de}$ for DE and find that $\delta(z)$ is likely to cross the non-interacting ($\delta=0$) and have an oscillation form. It suggests that to study the interaction between DE and DM, more general phenomenological forms of the interacting term should be considered.