In this paper we explore possible extensions of interacting dark energy cosmologies, where dark energy and dark matter interact nongravitationally with one another. In particular, we focus on the neutrino sector, analyzing the effect of both neutrino masses and the effective number of neutrino species. We consider the Planck 2018 legacy release data combined with several other cosmological probes, finding no evidence for new physics in the dark radiation sector. The current neutrino constraints from cosmology should therefore be regarded as robust, as they are not strongly dependent on the dark sector physics, once all the available observations are combined. Namely, we find a total neutrino mass $M_{\nu }<0.15\mathrm{eV}$ and a number of effective relativistic degrees of freedom $N_{\mathrm{eff}}=3.03_{-0.33}^{+0.33}$, both at 95% C.L., which are close to those obtained within the $\mathrm{\Lambda }\mathrm{CDM}$ cosmology, $M_{\nu }<0.12\mathrm{eV}$ and $N_{\mathrm{eff}}=3.00_{-0.35}^{+0.36}$, for the same data combination.

• Received 9 February 2020
• Accepted 24 March 2020

DOI:https://doi.org/10.1103/PhysRevD.101.083509