James Webb Space Telescope Feed Post

IOP Science: JWST CEERS and JADES Active Galaxies at z = 4–7 Violate the Local M•–M⋆ Relation at >3σ: Implications for Low-mass Black Holes and Seeding Models

Paper 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 Ha-detected black holes, we investigate (i) the high-zM•–M? relation and (ii) the black hole mass distribution, especially in its low-mass range (M• ? 106.5M?). With a detailed statistical analysis, our findings conclusively reveal a high-zM•–M? relation that deviates at >3s confidence level from the local relation. The high-z relation is \mathrm{log}({M}_{\bullet }/\,{M}_{\odot })=-{2.43}_{-0.83}^{+0.83}+{1.06}_{-0.09}^{+0.09}\mathrm{log}({M}_{\star }/\,{M}_{\odot }). Black holes are overmassive by ~10–100× 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× more black holes with M• ? 106.5M?, and 10–30× more with M• ? 108.5M?, compared to local relation’s predictions. The lighter black holes preferentially occupy galaxies with a stellar mass of ~107.5–108M?. We have yet to detect these sources because (i) they may be inactive (duty cycles 1%–10%), (ii) the host overshines the active galactic nucleus (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•–M? 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 coevolution with their galactic hosts.