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

TL;DR

This paper reports the discovery of an ultra-luminous quasar at redshift 6.30 with an exceptionally massive black hole of about 12 billion solar masses, challenging existing theories of early black hole growth.

Contribution

It presents the discovery and characterization of a highly luminous, high-redshift quasar with an extremely massive black hole, providing new insights into early universe black hole formation.

Findings

Black hole mass estimated at ~12 billion solar masses.

Proximity zone size of 26 million light years, larger than other z>6 quasars.

Luminosity exceeds that of previously known z>6 quasars.

Abstract

So far, roughly 40 quasars with redshifts greater than z=6 have been discovered. Each quasar contains a black hole with a mass of about one billion solar masses ($10^9 M_\odot$). The existence of such black holes when the Universe was less than 1 billion years old presents substantial challenges to theories of the formation and growth of black holes and the coevolution of black holes and galaxies. Here we report the discovery of an ultra-luminous 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 on the blue side of the Ly $\alpha$ emission line in the spectrum, we estimate the proper size of the ionized proximity zone associated with the quasar to be 26 million light years, larger than found with other z>6.1 quasars with lower luminosities. We estimate (on the basis of a near-infrared spectrum) that the black hole has a mass of $\sim 1.2 \times 10^{10} M_\odot$, which is consistent with the $1.3 \times 10^{10} M_\odot$ derived by assuming an Eddington-limited accretion rate.