Echo of interactions in the dark sector

Abstract

We investigate the observational constraints on an interacting vacuum energy scenario with two different neutrino schemes (with and without a sterile neutrino) using the most recent data from CMB temperature and polarization anisotropy, baryon acoustic oscillations (BAO), type Ia supernovae from JLA sample and structure growth inferred from cluster counts. We find that inclusion of the galaxy clusters data with the minimal data combination CMB + BAO + JLA suggests an interaction in the dark sector, implying the decay of dark matter particles into dark energy, since the constraints obtained by including the galaxy clusters data yield a non-null and negative coupling parameter between the dark components at 99\% confidence level. We deduce that the current tensions on the parameters $H_0$ and $\sigma_8$ can be alleviated within the framework of the interacting as well as non-interacting vacuum energy models with sterile neutrinos.