Properties of environment around AGN and luminous galaxy pairs through
  HSC wide survey
  We investigated the properties of AGN environments, particularly environments
where the association of luminous galaxies (LGs) is found within 4~Mpc from
AGNs with redshifts of 0.8 -- 1.1. For comparison, three additional AGN
environments, (namely, AGNs of all types, type~1 AGNs with X-ray and/or radio
detection, and type~2 AGNs) and an environment of blue $M_{*}$, characteristic
luminosity of the Schechter function, galaxies were investigated. The
cross-correlation function with the surrounding galaxies was measured and
compared between the AGN and blue galaxy samples. We also compared the
distributions of color, absolute magnitude, and stellar mass of the galaxies
around such target objects. The properties of clusters detected using
surrounding galaxies selected based on a photometric redshift were examined and
compared for different samples. The target AGNs were drawn from the Million
Quasars (MILLIQUAS) catalog, and the blue galaxies were drawn from six redshift
survey catalogs (SDSS, WiggleZ, DEEP2, VVDS, VIPERS, and PRIMUS). The galaxies
used as a measure of the environment around the targets are drawn from S18a
internal data released by the Hyper Suprime-Cam Subaru Strategic Program
(HSC-SSP). We found that, among the five AGN and blue galaxy samples
considered, the environment of AGN-LG pairs is the most enriched with luminous
galaxies. We also found an enhancement in the number of mass-selected clusters
in the AGN-LG pair sample against those in the other samples. The results
obtained in this study indicate that existence of multiple clusters is the
major driver in the association of AGNs and LGs, rather than a single
large-mass dark matter halo hosting the AGN.
