Clustering, Cosmology and a New Era of Black Hole Demographics -- II. The Conditional Luminosity Functions of Type 2 and Type 1 Active Galactic Nuclei

Abstract

The orientation-based unification model of active galactic nuclei (AGNs) posits that the principle difference between obscured (Type 2) and unobscured (Type 1) AGNs is the line-of-sight into the central engine. If this model is correct than there should be no difference in many of the properties of AGN host galaxies (e.g., the mass of the surrounding dark matter haloes). However, recent clustering analyses of Type 1 and Type 2 AGNs have provided some evidence for a difference in the halo mass, in conflict with the orientation-based unified model. In this work, a method to compute the Conditional Luminosity Function (CLF) of Type 2 and Type 1 AGNs is presented. The CLF allows many fundamental halo properties to be computed as a function of AGN luminosity, which we apply to the question of the host halo masses of Type 1 and 2 AGNs. By making use of the total AGN CLF, the Type 1 X-ray luminosity function, and the luminosity-dependent Type 2 AGN fraction, the CLFs of Type 1 and 2 AGNs are calculated at $z\approx 0$ and $0.9$. At both $z$, there is no statistically significant difference in the mean halo mass of Type 2 and 1 AGNs at any luminosity. There is marginal evidence that Type 1 AGNs may have larger halo masses than Type 2s, which would be consistent with an evolutionary picture where quasars are initially obscured and then subsequently reveal themselves as Type 1s. As the Type 1 lifetime is longer, the host halo will increase somewhat in mass during the Type 1 phase. The CLF technique will be a powerful way to study the properties of many AGNs subsets (e.g., radio-loud, Compton-thick) as future wide-area X-ray and optical surveys substantially increase our ability to place AGNs in their cosmological context.

10 pages, 11 figures, accepted by MNRAS

References in corpus (10)

• A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity
• Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-Thick Populations
• Absorption Properties and Evolution of Active Galactic Nuclei
• Obscuration-dependent evolution of Active Galactic Nuclei
• Towards a Concordant Model of Halo Occupation Statistics
• The Evolution of Obscuration in AGN
• The Angular Clustering of Infrared-Selected Obscured and Unobscured Quasars
• Clustering properties of moderate luminosity X-ray selected Type 1 and Type 2 AGN at z~3
• The Dark Matter Halos of Moderate Luminosity X-ray AGN as Determined from Weak Gravitational Lensing and Host Stellar Masses
• Clustering, Cosmology and a New Era of Black Hole Demographics -- I. The Conditional Luminosity Function of Active Galactic Nuclei

Cited by in corpus (7)

• The NuSTAR Serendipitous Survey: Hunting for The Most Extreme Obscured AGN at >10 keV
• Galaxy properties of type 1 and 2 X-ray selected AGN and comparison among different classification criteria
• The Black Hole Masses and Eddington Ratios of Type 2 Quasars
• A unified model for the clustering of quasars and galaxies at $z\approx 6$
• Revisiting the Extreme Clustering of $z\approx 4$ Quasars with Large Volume Cosmological Simulations
• Revisiting the clustering of narrow-line AGN in the local Universe: Joint dependence on stellar mass and color
• Clustering, Cosmology and a New Era of Black Hole Demographics -- I. The Conditional Luminosity Function of Active Galactic Nuclei