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

**Authors:** Haowen Zhang, Peter Behroozi, Marta Volonteri, Joseph Silk, Xiaohui Fan, James Aird, Jinyi Yang, Feige Wang, Philip F. Hopkins  
**arXiv:** [2309.07210](https://arxiv.org/abs/2309.07210)  
**Date:** 2023-09-13  
**Summary page:** https://www.summarizepaper.com/en/paper/2309.07210v1/

## Key points

- The number of supermassive black holes (SMBHs) with masses greater than $10^9$ solar masses in the observable Universe increases significantly from a redshift of approximately 10 to a redshift of around 2, and then further increases by a factor of about 3 from a redshift of 2 to the present day (redshift 0).
- At a redshift of approximately 6, SMBHs with masses greater than $10^9/10^{10}$ solar masses reside in halos with masses around $(2-3)/(3-5) \times 10^{12}$ solar masses.
- New active galactic nuclei (AGNs) observed by the James Webb Space Telescope (JWST) at redshifts ranging from approximately 7 to 11 are consistent with the predicted relation between SMBH mass and galaxy mass according to the TRINITY model.
- Runaway mergers in nuclear star clusters can potentially serve as progenitors for the observed SMBHs in GN-z11 (at a redshift of 10.6) and CEERS_1019 (at a redshift of 8.7), as suggested by the TRINITY model.
- Future wide area surveys conducted by telescopes like Roman and Euclid, focusing on quasars at high-redshift ranges from 6 to 10, will help reduce uncertainties in the relation between SMBH mass and galaxy mass by up to approximately 0.5 dex.
- The TRINITY model provides valuable insights into the evolution and properties of SMBHs at high redshifts, contributing to our understanding of their connection to galaxies and halos, as well as their formation and growth mechanisms.

## Summary

The TRINITY model presents predictions for the connection between high-redshift halos, galaxies, and supermassive black holes (SMBHs). The model is based on a comprehensive compilation of galaxy and SMBH datasets spanning redshifts from 0 to 10. The main findings of the TRINITY model are as follows: 1) The number of SMBHs with masses greater than $10^9$ solar masses in the observable Universe increases by six orders of magnitude from a redshift of approximately 10 to a redshift of around 2. This number then further increases by a factor of about 3 from a redshift of 2 to the present day (redshift 0). 2) At a redshift of approximately 6, SMBHs with masses greater than $10^9/10^{10}$ solar masses reside in halos with masses around $(2-3)/(3-5) \times 10^{12}$ solar masses. 3) The new AGNs (active galactic nuclei) observed by the James Webb Space Telescope (JWST) at redshifts ranging from approximately 7 to 11 are broadly consistent with the median relation between SMBH mass and galaxy mass for AGNs predicted by the TRINITY model. 4) The TRINITY model suggests that runaway mergers in nuclear star clusters can serve as viable progenitors for the SMBHs observed in GN-z11 (at a redshift of 10.6) and CEERS_1019 (at a redshift of 8.7). 5) Wide area surveys conducted by future telescopes such as Roman and Euclid, focusing on quasars at redshifts ranging from 6 to 10, will help reduce uncertainties in the relation between SMBH mass and galaxy mass at these high-redshift ranges by up to approximately 0.5 dex. Overall, the TRINITY model provides valuable insights into the evolution and properties of SMBHs at high redshifts, shedding light on their connection to galaxies and halos. The model's predictions contribute to our understanding of the formation and growth mechanisms of these massive cosmic objects.