X-Ray Evidence Against the Hypothesis that the Hyper-Luminous z = 6:3 Quasar J0100+2802 is Lensed

The z = 6:327 quasar SDSS J010013.02+280225.8 (hereafter J0100+2802) is believed to be powered by ablack hole more massive than 1010 M , making it the most massive black hole known in the first billion yearsof the Universe. However, recent high-resolution ALMA imaging shows four structures at the location of thisquasar, potentially implying that it is lensed with a magnification of 450 and thus its black hole is significantlyless massive. Furthermore, for the underlying distribution of magnifications of z & 6 quasars to producesuch an extreme value, theoretical models predict that a larger number of quasars in this epoch should be lensed,implying further overestimates of early black hole masses. To provide an independent constraint on the possibilitythat J0100+2802 is lensed, we re-analyzed archival XMM-Newton observations of the quasar and comparedthe expected ratios of X-ray luminosity to rest-frame UV and IR luminosities. For both cases, J0100+2802’sX-ray flux is consistent with the no-lensing scenario; while this could be explained by J0100+2802 being Xrayfaint, we find it does not have the X-ray or optical spectral features expected for an X-ray faint quasar.Finally, we compare the overall distribution of X-ray fluxes for known, typical z & 6 quasars. We find a 3 tensionbetween the observed and predicted X-ray-to-UV flux ratios when adopting the magnification probabilitydistribution required to produce a = 450 quasar.