Pōniuā‘ena: A Luminous z = 7.5 Quasar Hosting a 1.5 Billion Solar Mass Black Hole

Jinyi Yang, Feige Wang, Xiaohui Fan, Joseph F. Hennawi, Frederick B. Davies, Minghao Yue, Eduardo Banados, Xue Bing Wu, Bram Venemans, Aaron J. Barth, Fuyan Bian, Konstantina Boutsia, Roberto Decarli, Emanuele Paolo Farina, Richard Green, Linhua Jiang, Jiang Tao Li, Chiara Mazzucchelli, Fabian Walter

Research output: Contribution to journalArticlepeer-review

Abstract

We report the discovery of a luminous quasar, J1007+2115 at z = 7.515 (“Pōniuā‘ena”), from our wide-field reionization-era quasar survey. J1007+2115 is the second quasar now known at z > 7.5, deep into the reionization epoch. The quasar is powered by a (1.5 ± 0.2) × 109 M supermassive black hole (SMBH), based on its broad Mg II emission-line profile from Gemini and Keck near-IR spectroscopy. The SMBH in J1007+2115 is twice as massive as that in quasar J1342+0928 at z = 7.54, the current quasar redshift record holder. The existence of such a massive SMBH just 700 million years after the Big Bang significantly challenges models of the earliest SMBH growth. Model assumptions of Eddington-limited accretion and a radiative efficiency of 0.1 require a seed black hole of & 104 M at z = 30. This requirement suggests either a massive black hole seed as a result of direct collapse or earlier periods of rapid black hole growth with hyper-Eddington accretion and/or a low radiative efficiency. We measure the damping wing signature imprinted by neutral hydrogen absorption in the intergalactic medium (IGM) on J1007+2115’s Lyα line profile, and find that it is weaker than that of J1342+0928 and two other z & 7 quasars. We estimate an IGM volume-averaged neutral fraction hxHIi = 0.39+00..2213. This range of values suggests a patchy reionization history toward different IGM sightlines. We detect the 158 µm [C II] emission line in J1007+2115 with ALMA; this line centroid yields a systemic redshift of z = 7.5149 ± 0.0004 and indicates a star formation rate of ∼ 210 M yr1 in its host galaxy.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - Jun 23 2020

Keywords

  • Cosmology: observations
  • Early universe
  • Galaxies: active
  • Galaxies: high-redshift
  • Quasars: individual (UHS J100758.264+211529.207)

ASJC Scopus subject areas

  • General

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