Echo of interactions in the dark sector
  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.
