Reconstruction of the dark matter-vacuum energy interaction

TL;DR

This paper reconstructs the time evolution of the interaction between dark matter and vacuum energy using observational data, exploring its potential to resolve cosmological tensions but finding it not statistically favored over the standard model.

Contribution

It introduces a nonparametric Bayesian method to reconstruct the dark matter-vacuum energy interaction from multiple cosmological data sets.

Findings

Evolving interaction can alleviate some data tensions.

No significant Bayesian evidence favors interaction over ΛCDM.

Method provides a model-independent way to study dark sector interactions.

Abstract

An interaction between the vacuum energy and dark matter is an intriguing possibility which may offer a way of solving the cosmological constant problem. Adopting a general prescription for momentum exchange between the two dark components, we reconstruct $\alpha(a)$, the temporal evolution of the coupling strength between dark matter and vacuum energy, in a nonparametric Bayesian approach using combined observational data sets from the cosmic microwave background, supernovae and large scale structure. An evolving interaction between the vacuum energy and dark matter removes some of the tensions between different data sets. However, it is not preferred over $\Lambda$CDM in the Bayesian sense, as improvement in the fit is not sufficient to compensate for the increase in the volume of the parameter space.