Clustering, host galaxies, and evolution of AGN

TL;DR

This study investigates how different types of AGNs relate to their host galaxy properties, clustering, and evolution, revealing distinct environments and accretion modes linked to galaxy evolution stages.

Contribution

It provides new insights into the connection between AGN classes and host galaxy evolution, highlighting differences in halo mass, galaxy color, and accretion activity across wavebands.

Findings

Radio and X-ray AGNs are in large halos and red/green galaxies.

IR AGNs are in less luminous galaxies with higher Eddington ratios.

Quasar activity occurs in halos of 10^12-10^13 M_sun, marking a key evolutionary phase.

Abstract

We explore the connection between different classes of active galactic nuclei (AGNs) and the evolution of their host galaxies, by deriving host galaxy properties, clustering, and Eddington ratios of AGNs selected in the radio, X-ray, and infrared (IR) wavebands from the wide-field (9 deg^2) Bootes survey. We study a sample of 585 AGNs at 0.25 < z < 0.8 using redshifts from the AGN and Galaxy Evolution Survey (AGES). We find that radio and X-ray AGNs reside in relatively large dark matter halos (M_halo ~ 3x10^13 and 10^13 h^-1 M_sun, respectively) and are found in galaxies with red and "green" colors. In contrast, IR AGNs are in less luminous galaxies, have higher Eddington ratios, and reside in halos with M_halo < 10^12 M_sun. We interpret these results in terms of a general picture for AGNs and galaxy evolution, in which quasar activity is triggered when M_halo ~ 10^12 - 10^13 M_sun, after which star formation ceases and AGN accretion shifts to optically-faint, X-ray and radio-bright modes.