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We report X-ray observations of the most distant known gravitationally lensedquasar, J0439+1634 at $z=6.52$, which is also a broad absorption line (BAL)quasar, using the XMM-Newton Observatory. With a 130 ks exposure, the quasar issignificantly detected as a point source at the optical position with a totalof 358$^{+19}_{-19}$ net counts using the EPIC instrument. By fitting apower-law plus Galactic absorption model to the observed spectra, we obtain aspectral slope of $\Gamma=1.45^{+0.10}_{-0.09}$. The derived optical-to-X-rayspectral slope $\alpha_{\rm{ox}}$ is $-2.07^{+0.01}_{-0.01}$, suggesting thatthe X-ray emission of J0439+1634 is weaker by a factor of 18 than theexpectation based on its 2500 Angstrom luminosity and the average$\alpha_{\rm{ox}}$ vs. luminosity relationship. This is the first time that anX-ray weak BAL quasar at $z>6$ has been observed spectroscopically. Its X-rayweakness is consistent with the properties of BAL quasars at lower redshift. Byfitting a model including an intrinsic absorption component, we obtainintrinsic column densities of$N_{\rm{H}}=2.8^{+0.7}_{-0.6}\times10^{23}\,\rm{cm}^{-2}$ and $N_{\rm{H}}=4.3^{+1.8}_{-1.5}\times10^{23}\,\rm{cm}^{-2}$, assuming a fixed $\Gamma$ of 1.9and a free $\Gamma$, respectively. The intrinsic rest-frame 2--10 keVluminosity is derived as $(9.4-15.1)\times10^{43}\,\rm{erg\,s}^{-1}$, aftercorrecting for lensing magnification ($\mu=51.3$). The absorbed power-law modelfitting indicates that J0439+1634 is the highest redshift obscured quasar witha direct measurement of the absorbing column density. The intrinsic high columndensity absorption can reduce the X-ray luminosity by a factor of $3-7$, whichalso indicates that this quasar could be a candidate of intrinsically X-rayweak quasar.

Deep XMM-Newton Observations of an X-ray Weak, Broad Absorption Line Quasar at $z=6.5$