Holographic dark energy: constraints on the interaction from diverse
  observational data sets
  The present work deals with holographic dark energy models with Hubble
horizon as the infra-red cut-off. The interaction rate between dark energy and
dark matter has been reconstructed with three different choices of the
interaction term. It is shown that the coupling parameter of the interaction
term should evolve with redshift to allow the successful transition from
decelerated to accelerated phase of expansion. Constraints on the model
parameters are obtained from Markov Chain Monte Carlo (MCMC) analysis using the
supernova distance modulus data and observational measurements of the Hubble
parameter. Results show that the model with the coupling parameter increasing
with redshift (z) or equivalently decreasing with the evolution, are ruled out.
On the other hand, coupling parameters, increasing or slowly varying with the
evolution, are consistent with the observed evolution scenario. A Bayesian
evidence calculation has been carried out for statistical selection of the
reconstructed models. Though the kinematical parameters are well behaved for
these models, the physical variables which determine the nature of the
components in the matter sector, are not at all realistic. We have concluded
that the existence of spatial curvature is essential for this particular type
of dark energy models.
