Bañados, EduardoEduardoBañadosVenemans, Bram P.Bram P.VenemansMazzucchelli, ChiaraChiaraMazzucchelliFarina, Emanuele P.Emanuele P.FarinaWalter, FabianFabianWalterWang, FeigeFeigeWangDECARLI, ROBERTOROBERTODECARLIStern, DanielDanielSternFan, XiaohuiXiaohuiFanDavies, Frederick B.Frederick B.DaviesHennawi, Joseph F.Joseph F.HennawiSimcoe, Robert A.Robert A.SimcoeTurner, Monica L.Monica L.TurnerRix, Hans-WalterHans-WalterRixYang, JinyiJinyiYangKelson, Daniel D.Daniel D.KelsonRudie, Gwen C.Gwen C.RudieWinters, Jan MartinJan MartinWinters2020-09-252020-09-2520180028-0836http://hdl.handle.net/20.500.12386/27474Quasars are the most luminous non-transient objects known and as a result they enable studies of the Universe at the earliest cosmic epochs. Despite extensive efforts, however, the quasar ULAS J1120 + 0641 at redshift z = 7.09 has remained the only one known at z > 7 for more than half a decade. Here we report observations of the quasar ULAS J134208.10 + 092838.61 (hereafter J1342 + 0928) at redshift z = 7.54. This quasar has a bolometric luminosity of 4 × 10<SUP>13</SUP> times the luminosity of the Sun and a black-hole mass of 8 × 10<SUP>8</SUP> solar masses. The existence of this supermassive black hole when the Universe was only 690 million years old—just five per cent of its current age—reinforces models of early black-hole growth that allow black holes with initial masses of more than about 10<SUP>4</SUP> solar masses or episodic hyper-Eddington accretion. We see strong evidence of absorption of the spectrum of the quasar redwards of the Lyman α emission line (the Gunn-Peterson damping wing), as would be expected if a significant amount (more than 10 per cent) of the hydrogen in the intergalactic medium surrounding J1342 + 0928 is neutral. We derive such a significant fraction of neutral hydrogen, although the exact fraction depends on the modelling. However, even in our most conservative analysis we find a fraction of more than 0.33 (0.11) at 68 per cent (95 per cent) probability, indicating that we are probing well within the reionization epoch of the Universe.STAMPAenArticle10.1038/nature251802-s2.0-85041059570000423971100034https://www.nature.com/articles/nature251802018Natur.553..473BFIS/05 - ASTRONOMIA E ASTROFISICA