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

TL;DR

This study uses galaxy-galaxy lensing data from the HSC-SSP to measure dark matter halo masses of luminous AGNs across redshifts 0.2 to 1.2, revealing insights into their host galaxy properties and halo occupation.

Contribution

It provides the first detailed halo mass measurements of luminous AGNs using weak lensing from HSC-SSP, and explores the relationship between AGN activity and host halo mass.

Findings

Lensing detection around AGNs has a high signal-to-noise ratio of 29.

The halo mass profile of AGNs is consistent with massive galaxies.

Halo masses of AGNs in high stellar mass hosts fall below the stellar-to-halo mass relation.

Abstract

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 48907 AGNs constructed using HSC and WISE photometry. %The lensing detection around AGNs has a signal to noise ratio of \textbf{29}. As expected, we find that the lensing mass profile of total AGN sample is consistent with that of massive galaxies ($\rm log(M_{*}/h^{-2}M_\odot)\sim$ 10.61). Surprisingly, the lensing signal remains unchanged when the AGN sample is split into four stellar mass bins of host galaxies. 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 tends to suppress AGN activity, probably due to the lack of available gas.