An 800-million-solar-mass black hole in a significantly neutral Universe at a redshift of 7.5

• Published in: Nature (London) Vol. 553; no. 7689; pp. 473 - 476
• Main Authors: Bañados, Eduardo, Venemans, Bram P., Mazzucchelli, Chiara, Farina, Emanuele P., Walter, Fabian, Wang, Feige, Decarli, Roberto, Stern, Daniel, Fan, Xiaohui, Davies, Frederick B., Hennawi, Joseph F., Simcoe, Robert A., Turner, Monica L., Rix, Hans-Walter, Yang, Jinyi, Kelson, Daniel D., Rudie, Gwen C., Winters, Jan Martin
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 25.01.2018; Nature Publishing Group
• Subjects: 639/33/34; 639/33/34/124; Accretion; ASTRONOMY AND ASTROPHYSICS; Astrophysics; Black holes; Black holes (Astronomy); Bolometers; Deposition; Emission lines; Humanities and Social Sciences; Hydrogen; Intergalactic media; Ionization; letter; Luminosity; multidisciplinary; Natural history; Observations; Physics; Principal components analysis; Quasars; Red shift; Science; Science & Technology - Other Topics; Universe
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature25180

Observations of a quasar at redshift 7.54, when the Universe was just five per cent of its current age, suggest that the Universe was significantly neutral at this epoch. A massive black hole in the early Universe Despite extensive searches, only one quasar has been known at redshifts greater than 7, at 7.09. Eduardo Bañados and colleagues report observations of a quasar at a redshift of 7.54, when the Universe was just 690 million years old, with a black-hole mass 800 million times the mass of the Sun. The spectrum shows that the quasar's Lyman α emission is being substantially absorbed by an intergalactic medium containing significantly neutral hydrogen, indicating that reionization was not complete at that epoch. Quasars 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 1 . 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 13 times the luminosity of the Sun and a black-hole mass of 8 × 10 8 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 4 solar masses 2 , 3 or episodic hyper-Eddington accretion 4 , 5 . 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.