Properties of galaxies around AGNs with the most massive supermassive black holes revealed by clustering analysis

We present results of the clustering analysis between active galactic nuclei (AGNs) and galaxies at redshift 0.1-1.0, which was performed to investigate the properties of galaxies associated with the AGNs and reveal the nature of the fueling mechanism of supermassive black holes (SMBHs). We used 8059 AGNs/quasi-stellar objects (QSOs) for which virial masses of individual SMBHs were measured, and divided them into four mass groups. Cross-correlation analysis was performed to reconfirm our previous result that cross-correlation length increases with SMBH mass M-BH; we obtained consistent results. A linear bias of AGN for each mass group was measured as 1.47 for M-BH = 10(7.5)-10(8.2) M-circle dot and 3.08 for M-BH = 10(9)-10(10) M-circle dot. The averaged color and luminosity distributions of galaxies around the AGNs/QSOs were also derived for each mass group. The galaxy color Dopt-IR was estimated from a spectral energy distribution (SED) constructed from a catalog derived by merging the Sloan Digital Sky Survey (SDSS) and the UKIRT Infrared Deep Sky Survey (UKIDSS) catalogs. The distributions of color and luminosity were derived by a subtraction method, which does not require redshift information of galaxies. The main results of this work are as follows. (1) A linear bias increases by a factor of two from the lower-mass group to the highest-mass group. (2) The environment around AGNs with the most massive SMBHs (M-BH > 10(9) M-circle dot) is dominated by red sequence galaxies. (3) Marginal indication of decline in luminosity function at dimmer side of M-IR >-19.5 is found for galaxies around AGNs with M-BH = 10(8.2)-10(9) M-circle dot and nearest redshift group (z = 0.1-0.3). These results indicate that AGNs with the most massive SMBHs reside in haloes where a large fraction of galaxies have been transited to the red sequence. The accretion of hot halo gas as well as recycled gas from evolving stars can be one of the plausible mechanisms to fuel the SMBHs above similar to 10(9) M-circle dot.