Supernova Constraints on a holographic dark energy model

In this paper, we use the type Ia supernova data to constrain the model of holographic dark energy. For $d=1$, the best fit result is $\Omega^0_m = 0.25$, the equation of the state of the holographic dark energy $w^0_\d = -0.91$ and the transition between the decelerating expansion and the accelerating expansion happened when the cosmological red-shift was $z_T=0.72$. If we set $d$ as a free parameter, the best fit results are $d=0.21$, $\Omega_m^0=0.46$, $w_\d^0=-2.67$, which sounds like a phantom today, and the transition redshift is $z_T=0.28$.