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

Abstract

JWST is revolutionizing our understanding of the high-$z$ Universe by expanding the black hole horizon, looking farther and to smaller masses, and revealing the stellar light of their hosts. By examining JWST galaxies at $z=4-7$ that host H$\alpha$-detected black holes, we investigate (i) the high-$z$ $M_{\bullet }-M_{\star }$ relation and (ii) the black hole mass distribution, especially in its low-mass range ($M_{\bullet }\lesssim 10^{6.5}{M}_{\odot }$). With a detailed statistical analysis, our findings conclusively reveal a high-$z$ $M_{\bullet }-M_{\star }$ relation that deviates at $>3\sigma$ confidence level from the local relation. The high-$z$ relation is: $\log (M_{\bullet }/M_{\odot })=-2.43_{-0.83}^{+0.83}+1.06_{-0.09}^{+0.09}\log (M_{\star }/M_{\odot })$. Black holes are overmassive by $\sim 10-100\times$ compared to their low-$z$ counterparts in galactic hosts of the same stellar mass. This fact is not due to a selection effect in surveys. Moreover, our analysis predicts the possibility of detecting in high-$z$ JWST surveys $5-15\times$ more black holes with $M_{\bullet }\lesssim 10^{6.5}{M}_{\odot }$, and $10-30\times$ more with $M_{\bullet }\lesssim 10^{8.5}{M}_{\odot }$, compared to local relation's predictions. The lighter black holes preferentially occupy galaxies with a stellar mass of $\sim 10^{7.5}-10^8{M}_{\odot }$. We have yet to detect these sources because (i) they may be inactive (duty cycles $1\%-10\%$), (ii) the host overshines the AGN, or (iii) the AGN is obscured and not immediately recognizable by line diagnostics. A search of low-mass black holes in existing JWST surveys will further test the $M_{\bullet }-M_{\star }$ relation. Current JWST fields represent a treasure trove of black hole systems at $z=4-7$; their detection will provide crucial insights into their early evolution and co-evolution with their galactic hosts.

Accepted for publication in The Astrophysical Journal Letters. 14 pages, 5 figures

References in corpus (10)

• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The Sloan Digital Sky Survey Quasar Catalog: Sixteenth Data Release
• A Luminous Quasar at Redshift 7.642
• The GLASS James Webb Space Telescope Early Release Science Program. I. Survey Design and Release Plans
• The JWST Early Release Observations
• Initial mass function of intermediate mass black hole seeds
• Improved Dynamical Constraints on the Masses of the Central Black Holes in Nearby Low-mass Early-type Galactic Nuclei And the First Black Hole Determination for NGC 205
• Black hole scaling relations of active and quiescent galaxies: Addressing selection effects and constraining virial factors
• Feedback Limits to Maximum Seed Masses of Black Holes
• Dwarf Galaxies and the Black-Hole Scaling Relations

Cited by in corpus (3)

• Overmassive black holes at cosmic noon: linking the local and the high-redshift Universe
• Constraining the AGN luminosity function from JWST with the X-ray Background
• The Host Galaxy of a Dormant, Overmassive Black Hole at $z=6.7$ May Be Restarting Star Formation