Constraints to Holographic Dark Energy Model via Type Ia Supernovae,
  Baryon Acoustic Oscillation and WMAP
  In this paper, the holographic dark energy (HDE) model, where the future
event horizon is taken as an IR cut-off, is confronted by using currently
available cosmic observational data sets which include type Ia supernovae,
baryon acoustic oscillation and cosmic microwave background radiation from full
information of WMAP-7yr. Via the Markov Chain Monte Carlo method, we obtain the
values of model parameter $c= 0.696_{- 0.0737- 0.132- 0.190}^{+ 0.0736+ 0.159+
0.264}$ with $1,2,3\sigma$ regions. Therefore one can conclude that at lest
$3\sigma$ level the future Universe will be dominated by phantom like dark
energy. It is not consistent with positive energy condition, however this
condition must be satisfied to derive the holographic bound. It implies that
the current cosmic observational data points disfavor the HDE model.
