74 v 3 7 F eb 2 00 7 Particle vs . future event horizon in interacting holographic dark energy model

By choosing the future event horizon as the horizon of the flat FLRW universe, we show that the interacting holographic dark energy model is able to explain the phantom divide line crossing. We show that if one takes the particle event horizon as the horizon of the universe, besides describing ω = −1 crossing, (based on astrophysical data) he is able to determine appropriately the ratio of dark matter to dark energy density at transition time. In this approach, after the first transition from quintessence to phantom, there is another transition from phantom to quintessence phase which avoids the big rip singularity.