Direction Dependence of the Deceleration Parameter
  In this paper we study the possibly existing anisotropy in the acceleration
expansion by use of the full sample of Union2 data. Using the hemisphere
comparison method to search for a preferred direction, we take the deceleration
parameter q0 as the diagnostic to quantify the anisotropy level in the wCDM
model. We find that the maximum accelerating expansion direction is
$(l,b)=(314_{+20^{\circ}}^{\circ-13^{\circ}},28_{+11^{\circ}}^{\circ-33^{\circ}})$,with
the maximum anisotropy level of $\delta
q_{0,max}/\bar{q}_0=0.79_{+0.27}^{-0.28}$, and that the anisotropy is more
prominent when only low redshift data ($z\leq0.2$) are used. We also discuss
this issue in the $CPL$ parameterized model, showing a similar result.
