Dark calling Dark: Interaction in the dark sector in presence of neutrino properties after Planck CMB final release

TL;DR

This study explores interactions between dark energy and dark matter, incorporating neutrino properties, and finds evidence for a non-zero dark sector coupling that could address the H0 tension in cosmology.

Contribution

It extends previous dark sector interaction models by including neutrino parameters and demonstrates their impact on cosmological tensions and parameters.

Findings

Dark coupling can resolve the H0 tension.

Neutrino mass and effective number are consistent with standard expectations.

Evidence for non-zero dark sector coupling at over 3σ confidence level.

Abstract

We investigate a well known scenario of interaction in the dark sector where the vacuum energy is interacting with cold dark matter throughout the cosmic evolution in light of the cosmic microwave background (CMB) data from final Planck 2018 release. In addition to this minimal scenario, we generalize the model baseline by including the properties of neutrinos, such as the neutrino mass scale ($M_{\nu}$) and the effective number of neutrino species ($N_{\rm eff}$) as free parameters, in order to verify the possible effects that such parameters might generate on the coupling parameter, and vice versa. As already known, we again confirm that in light of the Planck 2018 data, such dark coupling can successfully solve the $H_0$ tension (with and without the presence of neutrinos). Concerning the properties of neutrinos, we find that $M_{\nu}$ may be wider than expected within the $\Lambda$CDM model and $N_{\rm eff}$ is fully compatible with three neutrino species (similar to $\Lambda$CDM prevision). The parameters characterizing the properties of neutrinos do not correlate with the coupling parameter of the interaction model. When considering the joint analysis of CMB from Planck 2018 and an estimate of $H_0$ from Hubble Space Telescope 2019 data, {\it we find an evidence for a non-null value of the coupling parameter at more than 3$\sigma$ confidence-level.} We also discuss the possible effects on the interacting scenario due to the inclusion of baryon acoustic oscillations data with Planck 2018. Our main results updating the dark sectors' interaction and neutrino properties in the model baseline, represent a new perspective in this direction. Clearly, a possible new physics in light of some dark interaction between dark energy and dark matter can serve as an alternative to $\Lambda$CDM scenario to explain the observable Universe, mainly in light of the current tension on $H_0$.