Model of interacting holographic dark energy at the Ricci scale

We study a holographic cosmological model in which the infrared cutoff is set by the Ricci length and dark matter and dark energy do not evolve on their own but interact nongravitationally with each other. This greatly alleviates the cosmic coincidence problem because the ratio between both components does not vanish at any time. We constrain the model with observational data from supernovae, cosmic background radiation, baryon acoustic oscillations, gas mass fraction in galaxy clusters, the history of the Hubble function, and the growth function.