Observational constraints on a holographic, interacting dark energy model

We constrain an interacting, holographic dark energy model, first proposed by two of us in [1], with observational data from supernovae, CMB shift, baryon acoustic oscillations, x-rays, and the Hubble rate. The growth function for this model is also studied. The model fits the data reasonably well but still the conventional $\Lambda$CDM model fares better. Nevertheless, the holographic model greatly alleviates the coincidence problem and shows compatibility at $1\sigma$ confidence level with the age of the old quasar APM 08279+5255.