Exploratory Chandra observation of the ultraluminous quasar SDSS
  J010013.02+280225.8 at redshift 6.30
  We report exploratory \chandra\ observation of the ultraluminous quasar SDSS
J010013.02+280225.8 at redshift 6.30. The quasar is clearly detected by
\chandra\ with a possible component of extended emission. The rest-frame 2-10
keV luminosity is 9.0$^{+9.1}_{-4.5}$ $\times$ 10$^{45}$ erg s$^{-1}$ with
inferred photon index of $\Gamma$ = 3.03$^{+0.78}_{-0.70}$. This quasar is
X-ray bright, with inferred X-ray-to-optical flux ratio \aox\
$=-1.22^{+0.07}_{-0.05}$, higher than the values found in other quasars of
comparable ultraviolet luminosity. The properties inferred from this
exploratory observation indicate that this ultraluminous quasar might be
growing with super-Eddington accretion and probably viewed with small
inclination angle. Deep X-ray observation will help to probe the plausible
extended emission and better constraint the spectral features for this
ultraluminous quasar.
