# JWST CEERS & JADES Active Galaxies at z = 4-7 Violate the Local $M_\bullet-M_\star$ Relation at $>3σ$: Implications for Low-Mass Black Holes and Seeding Models

**Authors:** Fabio Pacucci, Bao Nguyen, Stefano Carniani, Roberto Maiolino, Xiaohui Fan  
**arXiv:** [2308.12331](https://arxiv.org/abs/2308.12331)  
**Date:** 2023-08-23  
**Summary page:** https://www.summarizepaper.com/en/paper/2308.12331v1/

## Key points

- The James Webb Space Telescope (JWST) is expanding our knowledge of black holes in the high-z Universe.
- JWST has made new detections of high-z systems, providing insights into the formation of the first black holes and their co-evolution with galaxies.
- Researchers examined JWST galaxies at z=4-7 hosting Hα-detected black holes to investigate the high-z $M_\bullet-M_\star$ relation and the distribution of black hole masses.
- They found compelling evidence for a high-z $M_\bullet-M_\star$ relation that deviates significantly from the local relation, indicating overmassive black holes in high-z galaxies compared to their local counterparts.
- The analysis predicts an increased likelihood of detecting low mass black holes in future high z JWST surveys, particularly in galaxies with a stellar mass between approximately $10^{7.5}-10^8 M_{\odot}$.
- Potential challenges include inactive duty cycles, host galaxy overshadowing AGN, and obscured AGN not immediately recognizable through line diagnostics when detecting low mass black holes.
- Conducting searches for low mass black holes in existing JWST surveys will further test the relationship between them and their galactic hosts.
- This research has significant implications for understanding high z galaxies and their central supermassive black holes, shedding light on formation mechanisms and seeding models.

## Summary

The James Webb Space Telescope (JWST) is revolutionizing our understanding of the high-z Universe by expanding our knowledge of black holes. By looking farther and to smaller masses, as well as revealing the stellar light of their hosts, JWST has made new detections of high-z systems that offer unprecedented insights into the formation of the first black holes and their early co-evolution with galaxies. In a recent study, researchers examined JWST galaxies at z=4-7 that host Hα-detected black holes. Their goal was to investigate two main aspects: (i) the high-z $M_\bullet-M_\star$ relation and (ii) the distribution of black hole masses, particularly in its low-mass range ($M_\bullet\lesssim10^{6.5} M_\odot$). Through a detailed statistical analysis, they found compelling evidence for a high-z $M_\bullet-M_\star$ relation that deviates significantly from the local relation at a confidence level exceeding 3σ. Specifically, they derived a new relation given by $\log(M_\bullet/M_\odot) = -2.38^{+0.82}_{-0.83}+1.06^{+0.09}_{-0.09}\log(M_\star/M_\odot)$, which indicates that black holes in high-z galaxies are overmassive compared to their local counterparts in similar galactic hosts by approximately 10 to 100 times and cannot be attributed to selection effects in surveys. Furthermore, their analysis predicts an increased likelihood of detecting even more low mass black holes in future high z JWST surveys compared to predictions based on the local relation; specifically 5 to 18 times more with $M_\bullet \lesssim 10^{6.5} M_\odot$, and 10 to 30 times more with $M_\bullet \lesssim 10^{8.5} M_ \odot$. These lighter black holes are expected to preferentially occupy galaxies with a stellar mass between approximately $10^{7.5} - 10^8 M_{ \odot }$. The researchers also discussed potential challenges such as inactive duty cycles ranging from 1% to 10%, host galaxy overshadowing active galactic nuclei (AGN), or AGN being obscured and not immediately recognizable through line diagnostics when attempting detection of these low mass black holes . They suggest conducting searches for low mass black holes in existing JWST surveys will further test this relationship between them and their galactic hosts . Overall , this research has significant implications for our understanding of high z galaxies and their central supermassive black holes , providing crucial insights into early evolution and coevolution between them . Detecting these systems will shed light on formation mechanisms and seeding models , making current JWST fields a valuable resource for studying these phenomena .