A Model of Holographic Dark Energy

A model for holographic dark energy is proposed, following the idea that the short distance cut-off is related to the infrared cut-off. We assume that the infrared cut-off relevant to the dark energy is the size of the event horizon. With the input $\Omega_\Lambda=0.73$, we predict the equation of state of the dark energy at the present time be characterized by $w=-0.90$. The cosmic coincidence problem can be resolved by inflation in our scenario, provided we assume the minimal number of e-folds.