Constraining the AGN tori at cosmic noon using high-resolution JWST imaging and simultaneous SED fitting

Devang H. Liya, David J. Rosario, Matthaios Charidis

First listed 2025-10-30 | Last updated 2025-10-30

Abstract

There is evidence for significant evolution in the gaseous and dust properties of galaxies since the era of cosmic noon ($1\lesssim z\lesssim 2.5$). The well known co-evolution of supermassive black holes with their host galaxies suggests a constant connection between the small-scale (nuclear) and large-scale regions of galaxies. A fundamental component of Active Galactic Nuclei (AGN) is the "torus", a dense, dusty structure that acts as the interface between the accretion disc and the ISM of the host galaxy. The transitional nature of the torus makes it a prime subject to search for evolution since cosmic noon. We use high-resolution near- and mid-IR imaging from the JWST CEERS program to disentangle the emission from the torus in unprecedented detail for 88 X-ray selected AGN at $z\sim2$. We employ a novel SED fitting technique that combines archival low-resolution multi-band photometry at UV to FIR wavelengths with the new high-resolution JWST photometry to constrain essential AGN and torus parameters, such as accretion disc luminosity, torus opening angle, and inclination angle. We demonstrate that this SED fitting approach leads to better AGN characterisation and tighter constraints on AGN parameters. The population-level analysis finds that the Covering Fraction ($CF$) distribution peaks at $\approx0.25$ with a long tail towards higher $CF$. Despite the well-known evolution of the ISM and structural properties of AGN hosts to these redshifts, the $CF$ distribution of our sample does not show any strong statistical difference with that found in local AGN of equivalent luminosity, or with those at intermediate redshifts.

Short digest

Using CEERS near- and mid-IR imaging, the authors isolate nuclear emission and perform simultaneous SED fits that combine new high-resolution JWST photometry with archival UV–FIR data for 88 X-ray selected z≈2 AGN. Their Bayesian framework tightens constraints on accretion-disc luminosity and torus geometry, finding a covering-fraction distribution peaking near 0.25 with a long high-CF tail. At the population level, the CF distribution shows no strong statistical difference from local or intermediate-redshift AGN of similar luminosity, despite major ISM evolution at cosmic noon. This argues that torus geometry may be governed primarily by nuclear-scale processes rather than evolving host conditions.

Key figures to inspect

• Figure 1 (L2–10 keV vs. z with NH coding): Verify the luminosity and obscuration spread of the 88 CEERS/AEGIS-X AGN and how the dashed selection cuts define the final sample around z~2.
• Figure 2 (sky footprint with HST F160W): Check which sources have NIRCam, MIRI, or both; note how MIRI coverage anchors hot-dust constraints and how full HELP/AEGIS-X overlap supports multiwavelength SEDs.
• Figure 3 (workflow diagram): Follow the dual-SED pathway—central (nuclear) plus integrated photometry—into the Bayesian fit, noting where torus priors enter and how simultaneous fitting mitigates galaxy–torus degeneracies.
• Figure 4 (postage stamps for XID471): Examine the fixed F277W 80% EE nuclear aperture versus the CANDELS Kron radius to see host dilution control, and compare the AEGIS-X optical position to the JWST-recentered nucleus to gauge astrometric and contamination impacts.