Evidence for heavy seed origin of early supermassive black holes from a z~10 X-ray quasar

TL;DR

This paper reports the discovery of a massive, heavily-obscured quasar at redshift 10.3, supporting the hypothesis that early supermassive black holes originated from heavy seeds rather than light ones.

Contribution

It provides observational evidence for heavy seed black holes in the early universe through X-ray detection of a high-redshift quasar, aligning with theoretical predictions.

Findings

Detected a $10^7$-$10^8 M_{ m ext{sun}}$ black hole at z~10.3

Black hole mass comparable to host galaxy's stellar mass

Supports heavy seed black hole formation models

Abstract

Observations of quasars reveal that many supermassive black holes (BHs) were in place less than 700 million years after the Big Bang. However, the origin of the first BHs remains a mystery. Seeds of the first BHs are postulated to be either light (i.e., $10-100~\rm{M_{\odot}})$, remnants of the first stars or heavy (i.e., $10^4-10^5~\rm{M_{\odot}})$, originating from the direct collapse of gas clouds. Harnessing recent data from the Chandra X-ray Observatory, we report the detection of an X-ray-luminous massive BH in a gravitationally-lensed galaxy identified by JWST at $z\approx10.3$ behind the cluster lens Abell 2744. This heavily-obscured quasar with a bolometric luminosity of $L_{\rm bol}\sim5\times10^{45}~\rm{erg\ s^{-1}}$ harbors a $M_{\rm BH}\sim10^7-10^8~\rm{M_{\odot}}$ BH assuming accretion at the Eddington limit. This mass is comparable to the inferred stellar mass of its host galaxy, in contrast to what is found in the local Universe wherein the BH mass is $\sim0.1\%$ of the host galaxy's stellar mass. The combination of such a high BH mass and large BH-to-galaxy stellar mass ratio just $\sim$500 Myrs after the Big Bang was theoretically predicted and is consistent with a picture wherein BHs originated from heavy seeds.