A Single Intrinsic Luminosity Function for Both Type-I and Type-II Active Galactic Nuclei

Abstract

The luminous electromagnetic emission from distant active galactic nuclei (AGNs) including quasars is believed to be powered by accretion onto super-massive black holes (SMBHs). In the standard unification model for AGNs a dusty torus covers a significant portion of the viewing angles to the accretion disk and the BH. The system is classified as a type-I AGN if the accretion disk is viewed through the opening part; otherwise it is called a type-II AGN. Therefore the ratio of type-II to type-I AGNs serves as a sensitive probe to the unification model. A surprising discovery made from several large sky coverage and/or deep AGN surveys has found a significant anti-correlation between the type-II fraction and the observed X-ray luminosity between 2-10 keV. This suggests two different luminosity functions for the two types of AGNs, thus challenging the AGN unification model. However this observed anti-correlation is a natural consequence of the AGN unification model with only one intrinsic luminosity function if the inclination angle effects of the X-ray emitting accretion disk are taken into account. Thus the AGN unification model survived another critical test.

10 pages, 2 figures, submitted on 2004 Oct. 20 and accepted on 2004 Dec. 1 for publication in ApJ Letters

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• Kinematics of the Compact Symmetric Object OQ 208 revisited
• The radio structure of 3C 316, a galaxy with double-peaked narrow optical emission lines
• A population synthesis study on the faint X-ray sources in the Galactic center region
• Evolutionary Consequences of Dusty Tori in Active Galactic Nuclei
• Anisotropic radiation from accretion disc-coronae in active galactic nuclei
• Similar phenomena at different scales: Black Holes, the Sun, Gamma-ray Bursts, Supernovae, Galaxies and Galaxy Clusters
• Evolution of luminosity function and obscuration of AGN: connecting X-ray and Infrared
• The Intrinsic Quasar Luminosity Function: Accounting for Accretion Disk Anisotropy
• Relativistic effects on the observed AGN luminosity distribution