Properties of Galaxies around AGNs with Most Massive Supermassive Black Hole Revealed by the Clustering Analysis

TL;DR

This study investigates the environments of AGNs with the most massive supermassive black holes, revealing they are surrounded by red galaxies and suggesting hot halo gas accretion as a fueling mechanism.

Contribution

It provides new insights into the galaxy environments of high-mass SMBHs and links galaxy color distributions to SMBH mass and fueling processes.

Findings

Bias doubles from low to high SMBH mass groups.

High-mass SMBHs are in red galaxy-dominated environments.

Possible decline in galaxy luminosity function around certain SMBH masses.

Abstract

We present results of the clustering analysis between active galactic nuclei (AGNs) and galaxies at redshift 0.1-1.0 for investigating properties of galaxies associated with the AGNs, revealing the nature of fueling mechanism of supermassive black holes (SMBHs). We used 8059 SDSS AGNs/QSOs for which virial masses of individual SMBHs were measured, and divided them into four mass groups. Cross-correlation analysis was performed and bias for each mass group was derived. The averaged color and luminosity distributions of galaxies around the AGNs/QSOs were also derived for each mass group. The galaxy color was estimated for SED constructed from a merged SDSS and UKIDSS catalog. The distributions of color and luminosity were derived by the subtraction method, which does not require redshift information of galaxies. The main results of this work are: (1) a bias increases by a factor two from the lower mass group to the highest mass group; (2) the environment around AGNs with the most massive SMBH (Mbh > 10^9 Msun) is dominated by red sequence galaxies; (3) marginal indication of decline in luminosity function at dimmer side of M > -19.5 mag is found for galaxies around AGNs with Mbh = 10^8.2 - 10^9 Msun and nearest redshift group (z=0.1-0.3). These results indicate that AGNs with the most massive SMBHs reside in haloes where 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 the most plausible mechanism to fuel the SMBHs above ~10^9 Msun.