Cross-correlation of Luminous Red Galaxies with ML-selected Active Galactic Nuclei in HSC-SSP. III. HOD Parameters for Type I and Type II Quasars

Abstract Understanding the dark matter (DM) halo environment in which galaxies that host active galactic nuclei (AGNs) reside is a window into the nature of supermassive black hole (SMBH) accretion. We apply halo occupation distribution (HOD) modeling tools to interpret the angular cross-correlation functions between 1.5 × 10 6 luminous red galaxies and our ∼28,500 Hyper Suprime-Cam + Wide-field Infrared Survey Explorer-selected (and L 6 μ m -limited) AGNs to infer the halo properties of distinct quasar samples at physical scales s > 0.1 Mpc, for z ∈ 0.7–1.0. We find that Type I (unobscured) and Type II (obscured) AGNs cluster differently, both on small and large physical scales. The derived HODs imply that Type I AGNs reside, on average, in substantially (∼3×) more massive halos ( M h ∼ 10 13.4 M ⊙ ) than Type II AGNs ( M h ∼ 10 12.9 M ⊙ ) at >5 σ significance. While Type II AGNs show one-halo correlations similar to that of galaxies of their average halo mass, the Type I AGN intra-halo clustering signal is significantly shallower. We interpret this observation with HOD methods and find Type I AGNs are significantly less likely ( f sat ∼ 0.0 5 − 0.05 + 1 % ) to be found in satellite galaxies than Type II AGNs. We find reddened + obscured AGNs have typical satellite fractions for their halo mass ( M h ∼ 10 13 M ⊙ ), with f sat ∼ 2 0 − 5 + 10 % . Our results pose a significant challenge to the strict unified AGN morphological model, and instead suggest that a quasar’s spectral class is strongly correlated with its host galaxy’s DM halo environment. These intriguing results have provided a more complex picture of the SMBH–DM halo connection, and motivate future analyses of the intrinsic galaxy and accretion properties of AGNs.