JADES: comprehensive census of broad-line AGN from Reionization to Cosmic Noon revealed by JWST

Ignas Juodžbalis, Roberto Maiolino, William M. Baker, Emma Curtis Lake, Jan Scholtz, Francesco D'Eugenio, Bartolomeo Trefoloni, Yuki Isobe, Sandro Tacchella, Andrew J. Bunker, Stefano Carniani, Stéphane Charlot, Gareth C. Jones, Eleonora Parlanti, Michele Perna, Pierluigi Rinaldi, Brant Robertson, Hannah Übler, Giacomo Venturi, Chris Willott

First listed 2025-04-04 | Last updated 2025-04-29

Abstract

The depth and coverage of the first years of JWST observations have revealed low luminosity active galactic nuclei (AGN) across a wide redshift range, shedding light on black hole (BH) assembly and feedback. We present our spectroscopic sample of 34 Type 1 AGN obtained from JADES survey data and spanning $1.5 < z < 9$. Our sample of AGN probes a BH mass range of $10^{6-9}$~M$_{\odot}$ at bolometric luminosities down to $10^{43}$~erg~s$^{-1}$, implying generally sub-Eddington ratios of $<0.5L_{\rm Edd}$. Most of these AGN are hosted in low mass ($M_{\star}\sim10^8$~M$_{\odot}$) galaxies and are overmassive relative to the local $M_{BH}-M_{\star}$ relation, while remaining consistent with the local $M_{BH}$-$σ_*$ relation. The wide redshift range provided by our sample allows us to trace the emergence of local $M_{BH}$-$M_*$ scaling relation across the cosmic epoch. Additionally, we explore the capability of narrow-line diagnostics in identifying Type 2 AGN and find that a significant fraction of our AGN would be missed by them due to low metallicity or lack of high energy ionizing photons (potentially due to dust absorption, dense gas blanketing the broad and narrow line regions, or intrinsically soft ionizing spectra). We explore the UV luminosity function of AGN and their hosts and find that it is subject to significant cosmic variance and is also dependent on the AGN bolometric luminosity. Finally, we show that the electron and Balmer scattering scenarios recently proposed to explain the broad components of the Balmer lines are untenable on multiple grounds. There is no evidence that the black hole masses have been overestimated by orders of magnitude as proposed in those scenarios.

Short digest

Using JADES spectroscopy, the authors assemble a uniform census of 34 broad-line (Type 1) AGN spanning 1.5<z<9 with virial black-hole masses of 10^6–10^9 M⊙ and bolometric luminosities down to 10^43 erg s^-1, generally at sub-Eddington rates (<0.5 L_Edd). These AGN are typically in low-mass (M⋆≈10^8 M⊙) hosts whose black holes are overmassive relative to the local M_BH–M⋆ relation yet consistent with the local M_BH–σ⋆ relation, enabling a view of how these scalings emerge across cosmic time. The team shows that standard narrow-line diagnostics would miss many counterparts—especially at low metallicity or with attenuated/soft ionizing continua—complicating Type 2 selection. They also find strong cosmic-variance sensitivity in the UV luminosity function and rule out electron/Balmer scattering as the origin of broad Balmer components, arguing BH masses are not severely overestimated.

Key figures to inspect

• Figure 1: Inspect the prism+R1000 fits across redshift to see how BLR H-line widths and profiles are identified in diverse hosts, including a low-z case flagged as tentative due to [O III] outflows and a high-z, low-luminosity AGN; note the NIRCam stamps and slit placement for host context.
• Figure 2: Examine where the JADES broad-line sources lie in the M_BH–L_bol plane relative to prior samples and constant L/L_Edd tracks; verify the predominantly sub-Eddington regime and the caution that the apparent trend may be inflated by H-based scalings on both axes.
• Figure 3: Compare velocity-dispersion inferences from medium/high-resolution data versus R1000; learn that R1000 overestimates σ by ~80% after LSF correction, impacting dynamical interpretations and tests of the M_BH–σ⋆ relation.
• Figure 4: Check host stellar-mass systematics by contrasting ForcePho-based masses with prism-spectrum and photometry-only fits; assess offsets/uncertainties that set the placement of these low-mass hosts on the M_BH–M⋆ plane.