Interacting dark matter and modified holographic Ricci dark energy plus
  a noninteracting cosmic component
  We investigate a spatially flat Friedmann-Robertson-Walker universe that has
an interacting dark matter, a modified holographic Ricci dark energy (MHRDE),
plus a third, decoupled component that behaves as a radiation term. We consider
a nonlinear interaction in the dark component densities and their derivatives
up to second order. We apply the $\chi^{2}$ method to the observational Hubble
data for constraining the cosmological parameters and analyze the amount of
dark energy in the radiation era for both MHRDE and holographic Ricci dark
energy models. The former is consistent with the bound $\Omega_{x}(z\simeq
1100)<0.1$ reported for the behavior of dark energy at early times while the
latter does not fulfill it.
