# UNCOVER: The growth of the first massive black holes from JWST/NIRSpec -- spectroscopic confirmation of an X-ray luminous AGN at z=10.1

**Authors:** Andy D. Goulding, Jenny E. Greene, David J. Setton, Ivo Labbe, Rachel Bezanson, Tim B. Miller, Hakim Atek, Akos Bogdan, Gabriel Brammer, Iryna Chemerynska, Sam E. Cutler, Pratika Dayal, Yoshinobu Fudamoto, Seiji Fujimoto, Lukas J. Furtak, Vasily Kokorev, Gourav Khullar, Joel Leja, Danilo Marchesini, Priyamvada Natarajan  
**arXiv:** [2308.02750](https://arxiv.org/abs/2308.02750)  
**Date:** 2023-08-05  
**Summary page:** https://www.summarizepaper.com/en/paper/2308.02750v1/

## Key points

- The James Webb Space Telescope (JWST) has detected early black holes transitioning from "seeds" to supermassive black holes.
- UHZ-1, an X-ray luminous supermassive black hole, has been reported with a photometric redshift at z > 10.
- JWST's NIRSpec instrument has confirmed the existence of UHZ-1 and determined its spectroscopic redshift to be z = 10.073 +/- 0.002.
- UHZ-1 exhibits characteristics typical of recently discovered galaxies at z~10, primarily characterized by star-formation features.
- No clear evidence of the powerful X-ray source associated with UHZ-1 is observed in the rest-frame UV/optical spectrum, suggesting heavy obscuration of the central black hole.
- A stellar population fit was performed, resulting in a better estimate of the host galaxy's stellar mass (M* ~ 1.4 x 10^8 Msun) compared to previous estimates.
- The ratio of black hole mass (M_BH) to stellar mass (M*) remains two to three orders of magnitude higher than local values, indicating supermassive black holes were likely formed through a heavy seeding channel within the first billion years of cosmic evolution.
- This study highlights JWST's capabilities in detecting and confirming distant black holes and provides insights into their formation and growth processes during early cosmic history.

## Summary

The James Webb Space Telescope (JWST) has made a groundbreaking discovery, detecting early black holes (BHs) as they transition from "seeds" to supermassive BHs. In a recent study by Bogdan et al. (2023), an X-ray luminous supermassive black hole named UHZ-1 was reported with a photometric redshift at z > 10. This extreme source at such a high redshift provides valuable insights into the seeding and growth models for BHs, considering the limited time available for their formation and growth. Building upon this discovery, the researchers have now confirmed the existence of UHZ-1 using JWST's NIRSpec instrument. They have determined its spectroscopic redshift to be z = 10.073 +/- 0.002, further solidifying its position as one of the most distant known objects in the universe. The spectrum obtained from NIRSpec/Prism reveals that UHZ-1 exhibits characteristics typical of recently discovered galaxies at z~10, primarily characterized by star-formation features. Interestingly, no clear evidence of the powerful X-ray source associated with UHZ-1 is observed in the rest-frame UV/optical spectrum. This suggests that there may be heavy obscuration of the central BH, which aligns with the Compton-thick column density measured in X-rays. The presence of such heavy obscuration indicates that significant amounts of material surround and obscure the central BH. To gain further insights into UHZ-1 and its host galaxy, a stellar population fit was performed using both the new NIRSpec spectroscopy data and previously available photometry. This analysis resulted in a significantly better constrained estimate of the stellar mass for the host galaxy (M* ~ 1.4 x 10^8 Msun) compared to previous photometric estimates. Notably, when comparing the ratio of black hole mass (M_BH) to stellar mass (M*), it remains two to three orders of magnitude higher than local values - indicating that supermassive BHs were likely formed through a heavy seeding channel within the first billion years of cosmic evolution. Overall, this study highlights JWST's remarkable capabilities in detecting and confirming distant black holes and provides valuable insights into their formation and growth processes during early stages of cosmic history.