Tracing Obscured AGN Contribution and Number Fraction Across 0 < z < 6 with JWST

Angel Rodriguez Barbosa, Tomotsugu Goto, Daryl Joe D. Santos, Chih-Teng Ling, Tetsuya Hashimoto, Ece Kilerci, Priyanka Jalan, Terry Long Phan, Deriyan Senjaya, Vignesh V. V. Rao, Bahareh S. Salmasi

First listed 2026-07-29 | Last updated 2026-07-28

Abstract

Active galactic nuclei (AGN) are key drivers of galaxy evolution, yet many remain undetected in ultraviolet and optical surveys due to heavy dust obscuration. In these systems, absorbed emission is re-radiated at infrared (IR) wavelengths, making IR observations essential for identifying the full AGN population. Tracking the AGN IR contribution and number fraction provides insight into both the dominance and prevalence of AGN activity across cosmic time. Using the JWST Systematic Mid-infrared Instrument Legacy Extragalactic Survey (SMILES) and the JWST Advanced Deep Extragalactic Survey (JADES), we leverage continuous optical-to-mid-IR coverage (0.4-25 $μ$m) in the GOODS-S field to identify obscured AGN via multi-wavelength SED fitting with CIGALE. Our sample includes 278 AGN across 0 < z < 6, representing a seven-fold increase in sample size relative to previous studies utilizing the Cosmic Evolution Early Release Science (CEERS) survey due to the larger 15-pointing SMILES MIRI footprint. We find that both AGN IR contribution and number fraction increase with redshift, with AGN fractions rising from $\lesssim$ 5% at z < 2 to ~ 30% at higher redshifts, while the median AGN contribution increases by up to ~ 0.15. In contrast, as a function of total IR luminosity over $\log(L/L_{\odot}) \approx$ 8 - 12, the AGN contribution and AGN number fraction remain fundamentally static. These trends suggest that the prevalence of obscured AGN activity is dependent on redshift while showing little to no dependence on total infrared luminosity. Our results highlight JWST's ability to uncover previously hidden AGN populations and provide new constraints on AGN-galaxy co-evolution.

Short digest

Using 0.4–25 μm photometry from the SMILES MIRI and JADES programs in GOODS-S, the authors fit multi-wavelength SEDs with CIGALE to identify 278 obscured AGN over 0 < z < 6, a seven-fold expansion over their earlier CEERS-based sample. Both the AGN infrared contribution and AGN number fraction rise with redshift: the reported AGN fraction grows from 5% at z < 2 to roughly 30% at higher redshift, while the median AGN contribution increases by up to 0.15. In contrast, neither metric shows a fundamental dependence on total IR luminosity, arguing that the prevalence of JWST-revealed obscured accretion is primarily an epoch-dependent demographic effect rather than a simple function of host IR output.

Key figures to inspect

• Figure 1. This sample-definition figure maps total IR luminosity against redshift for every galaxy and color-codes sources by their fitted AGN IR fraction. It is the essential visual context for the paper’s demographic claims, showing the redshift and luminosity coverage from which the obscured-AGN fraction and AGN-contribution trends are measured.