Dark matter halos of luminous AGNs from galaxy-galaxy lensing with the HSC Subaru Strategic Program

We assess the dark matter halo masses of luminous AGNs over the redshift range 0.2 to 1.2 using galaxy-galaxy lensing based on imaging data from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). We measure the weak lensing signal of a sample of 8882 AGNs constructed using HSC and WISE photometry. The lensing detection around AGNs has a signal-to-noise ratio of 15. As expected, we find that the lensing mass profile is consistent with that of massive galaxies ($M_{*}\sim 10.8~M_\odot$). Surprisingly, the lensing signal remains unchanged when the AGN sample is split into low and high stellar mass hosts. Specifically, we find that the excess surface density (ESD) of AGNs, residing in galaxies with high stellar masses, significantly differs from that of the control sample. We further fit a halo occupation distribution model to the data to infer the posterior distribution of parameters including the average halo mass. We find that the characteristic halo mass of the full AGN population lies near the knee ($\rm log(M_h/h^{-1}M_{\odot})=12.0$) of the stellar-to-halo mass relation (SHMR). Illustrative of the results given above, the halo masses of AGNs residing in host galaxies with high stellar masses (i.e., above the knee of the SHMR) falls below the calibrated SHMR while the halo mass of the low stellar mass sample is more consistent with the established SHMR. These results indicate that massive halos with higher clustering bias tend to suppress AGN activity, probably due to the lack of available gas.
Comment: 17 pages,10 figures, accepted for publication in the Astrophysical Journal