TRINITY IV: Predictions for Supermassive Black Holes at $z\gtrsim 7$

Abstract

We present predictions for the high-redshift halo-galaxy-supermassive black hole (SMBH) connection from the TRINITY model. Constrained by a comprehensive compilation of galaxy ($0\le z\le 10$) and SMBH datasets ($0\le z\le 6.5$), TRINITY finds: 1) The number of SMBHs with $M_{\bullet }>10^9{M}_{\odot }$ in the observable Universe increases by six orders of magnitude from $z\sim 10$ to $z\sim 2$, and by another factor of $\sim 3$ from $z\sim 2$ to $z=0$; 2) The $M_{\bullet }>10^9/10^{10}{M}_{\odot }$ SMBHs at $z\sim 6$ live in haloes with $\sim (2-3)/(3-5)\times 10^{12}{M}_{\odot }$; 3) the new JWST AGNs at $7\lesssim z\lesssim 11$ are broadly consistent with the median SMBH mass-galaxy mass relation for AGNs from TRINITY; 4) Seeds from runaway mergers in nuclear star clusters are viable progenitors for the SMBHs in GN-z11 ($z=10.6$) and CEERS_1019 ($z=8.7$); 5) $z=6-10$ quasar luminosity functions from wide area surveys by, e.g., Roman and Euclid, will reduce uncertainties in the $z=6-10$ SMBH mass-galaxy mass relation by up to $\sim 0.5$ dex.

15 pages, 12 figures, submitted to MNRAS. Questions and comments are welcome!