Cross-correlation of Luminous Red Galaxies with ML-selected Active Galactic Nuclei in HSC-SSP. II. AGN Classification and Clustering with DESI Spectroscopy

Abstract An unresolved question in studies of active galactic nuclei (AGNs) is whether their distinct classes probe different evolutionary stages of black hole–host galaxy interaction. We present the projected two-point cross-correlation function between a sample of Dark Energy Spectroscopic Instrument (DESI)-matched AGNs selected from Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) optical + Wide-field Infrared Survey Explorer (WISE) mid-IR photometry, and DESI-designated luminous red galaxies (LRGs), for z ∈ 0.5–1.0. The total overlap area is 43.4 deg 2 , including ∼27,000 spectroscopic LRGs. We visually classified 1991 matched HSC×DESI objects in our redshift range, spectroscopically confirming that 1517 (76%) of them are AGNs. Of these 1517 objects, 73% are broad-line AGNs, and 27% are obscured AGNs. We infer that the parent HSC+WISE AGN catalog has a number density of at least ∼240 deg −2 , confirming it is one of the most complete optical/infrared AGN catalogs to date. We investigate the AGN clustering as a function of the spectroscopic classification. The inferred average mass of the halos 〈 M h 〉 that host unobscured broad-line AGNs ( M h ≈ 10 13.4 h −1 M ⊙ ) is ∼5.5 × larger than the halos that host obscured AGNs ( M h ≈ 10 12.6 h −1 M ⊙ ), at 2.8 σ significance, in the same sense as our prior work based on photometric redshifts. This suggests that we may relax our concerns about systematic shifts in the inferred redshift distribution producing this halo mass difference. While we do not yet find statistically significant spectroscopic evidence that unobscured AGNs reside in more-massive halos than their obscured counterparts, further analyses are necessary to distinguish if more complex evolutionary histories are needed to model these AGN populations.