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 Ω_Λ=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-foldings.