A Luminous Quasar at Redshift 7.642

Abstract

Distant quasars are unique tracers to study the formation of the earliest supermassive black holes (SMBHs) and the history of cosmic reionization. Despite extensive efforts, only two quasars have been found at z ≥ 7.5, due to a combination of their low spatial density and the high contamination rate in quasar selection. We report the discovery of a luminous quasar at z = 7.642, J0313−1806, the most distant quasar yet known. This quasar has a bolometric luminosity of 3.6 × 1013 L ⊙. Deep spectroscopic observations reveal a SMBH with a mass of (1.6 ± 0.4) × 109 M ⊙ in this quasar. The existence of such a massive SMBH just ∼670 million years after the big bang challenges significantly theoretical models of SMBH growth. In addition, the quasar spectrum exhibits strong broad absorption line (BAL) features in C iv and Si iv, with a maximum velocity close to 20% of the speed of light. The relativistic BAL features, combined with a strongly blueshifted C iv emission line, indicate that there is a strong active galactic nucleus (AGN)-driven outflow in this system. Atacama Large Millimeter/submillimeter Array observations detect the dust continuum and [C ii] emission from the quasar host galaxy, yielding an accurate redshift of 7.6423 ± 0.0013 and suggesting that the quasar is hosted by an intensely star-forming galaxy, with a star formation rate of ∼200 M ⊙ yr−1 and a dust mass of ∼7 × 107 M ⊙. Follow-up observations of this reionization-era BAL quasar will provide a powerful probe of the effects of AGN feedback on the growth of the earliest massive galaxies.

Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe’s First Billion Years

“…The evolution of supermassive black holes (SMBHs) in the early universe represents a challenge for modern cosmology, requiring significant, sustained growth from primordial seeds to explain the population of observed quasars in the first billion years of the universe (e.g., Inayoshi et al 2020). In the past decade, not only has the number of known members of this population expanded through large surveys (e.g., Bañados et al 2016;Jiang et al 2016;Mazzucchelli et al 2017;Reed et al 2017;Matsuoka et al 2019;Wang et al 2019;Yang et al 2019), but individual discoveries have pushed out the extremes of mass (Wu et al 2015;Yang et al 2020), luminosity (Pons et al 2019;Medvedev et al 2020), and redshift (Mortlock et al 2011;Bañados et al 2018c;Wang et al 2021b) that must be accounted for by theoretical models. Grappling with this challenge requires not only measuring quasar accretion rates, but also identifying mechanisms being used to produce massive growth.…”

Gravastars in a non-minimally coupled gravity with electromagnetism

“…Moreover, by considering alternative gravity models such as Kaluza-Klein theory this limit can reach much higher values [57] which is very close to our result z = 4. The authors of a very recent paper inform the discovery of a luminous quasar at z = 7.642, J0313-806 and the most distant quasar observed so far [51]. Besides, the surface redshift can be indefinitely large for quasiblack holes [58][59][60].…”

“…Compared with our previous model which has only one free parameter k, in this model we have a new arbitrary parameter β along with k. As usual the observational extreme values will guide us to determine the limits of β. According to the literature [49][50][51] more than 750,000 quasars have been found as for today. All observed quasar spectra have redshifts between 0.056 and 7.642.…”

Investigating close binary supermassive black holes at high angular resolution

“…Their "extra-power" is unlike the stellar nuclear fusion and is universally assumed to be an actively accreting central SMBH (Zeldovich and Novikov 1964, Salpeter 1964, Rees 1984. Their prominent observational signatures that cover the full electromagnetic spectrum include (see Padovani et al 2017, for a thorough review): masses ≥ 10 6 M ; very high luminosities (up to L bol ∼ 10 48 erg s −1 ), setting them as the strongest non-explosive sources in the observable Universe, detectable up to very high redshifts (currently z ∼ 7.642, Wang et al 2021); compact emitting regions (∼ Mpc) in most bands, and broad-band emission covering almost the entire electromagnetic spectrum. In a unified model, an AGN's SMBH is surrounded by a subparsec geometrically thin accretion disc threaded by strong magnetic fields and a dusty torus (Antonucci 1993, Urry andPadovani 1995).…”