2016ApJ...823L..37A

We report exploratory Chandra observations 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}_{-4.5}^{+9.1} ×10⁴⁵ erg/s with an inferred photon index of Γ= {3.03}_{-0.70}^{+0.78} . This quasar is X-ray bright, with an inferred X-ray-to-optical flux ratio α_ox = -{1.22}_{-0.05}^{+0.07} , 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 a small inclination angle. Deep X-ray observations will help to probe the plausible extended emission and better constrain the spectral features for this ultraluminous quasar.