An ultraluminous quasar with a twelve-billion-solar-mass black hole at redshift 6.30

• Published in: Nature (London) 2015-02, Vol.518 (7540), p.512-515
• Main Authors: Wu, Xue-Bing, Wang, Feige, Fan, Xiaohui, Yi, Weimin, Zuo, Wenwen, Bian, Fuyan, Jiang, Linhua, McGreer, Ian D., Wang, Ran, Yang, Jinyi, Yang, Qian, Thompson, David, Beletsky, Yuri
• Format: Article
• Language: English
• Subjects: 639/33/34/124; Accretion; Astronomical research; Black holes; Black holes (Astronomy); Gravity; Humanities and Social Sciences; letter; multidisciplinary; Observations; Quasars; Red shift; Science; Spectra; Spectrum analysis; Star & galaxy formation; Surveys
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature14241

Observations of an ultraluminous quasar, SDSS J010013.02+280225.8, at redshift z = 6.30 show that the object has an optical and near-infrared luminosity a few times greater than those of previously known quasars at z  > 6; the black hole that drives the quasar has a mass about 12 billion times that of the Sun. Ultraluminous quasar illuminates epoch of cosmic reionization Cosmic redshifts of between 6 and 7 represent a time when the intergalactic medium was in transition from a neutral state to being completely ionized. Here Xue-Bing Wu et al . report the discovery of an ultraluminous quasar at redshift z = 6.30 that has optical and near-infrared luminosity several times greater than previously known quasars at redshifts beyond 6. Based on near-infrared spectral data, the authors estimate a mass of approximately twelve-billion solar-masses for the associated black hole, consistent with the thirteen-billion solar masses derived by assuming an Eddington-limited accretion rate, where the force of radiation acting outwards and the gravitational force acting inwards are in balance. As the most luminous quasar known to date at z = 6, this object will be a useful resource for the study of galaxy formation around massive black holes at the end of the epoch of cosmic reionization. So far, roughly 40 quasars with redshifts greater than z = 6 have been discovered 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 . Each quasar contains a black hole with a mass of about one billion solar masses (10 9 ) 2 , 6 , 7 , 9 , 10 , 11 , 12 , 13 . The existence of such black holes when the Universe was less than one billion years old presents substantial challenges to theories of the formation and growth of black holes and the coevolution of black holes and galaxies 14 . Here we report the discovery of an ultraluminous quasar, SDSS J010013.02+280225.8, at redshift z = 6.30. It has an optical and near-infrared luminosity a few times greater than those of previously known z  > 6 quasars. On the basis of the deep absorption trough 15 on the blue side of the Lyman-α emission line in the spectrum, we estimate the proper size of the ionized proximity zone associated with the quasar to be about 26 million light years, larger than found with other z  > 6.1 quasars with lower luminosities 16 . We estimate (on the basis of a near-infrared spectrum) that the black hole has a mass of ∼1.2 × 10 10 , which is consistent with the 1.3 × 10 10 derived by assuming an Eddington-limited accretion rate.