A Single Intrinsic Luminosity Function for Both Type-I and Type-II Active Galactic Nuclei
摘要
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.
引用
@article{arxiv.astro-ph/0412043,
title = {A Single Intrinsic Luminosity Function for Both Type-I and Type-II Active Galactic Nuclei},
author = {Shuang Nan Zhang},
journal= {arXiv preprint arXiv:astro-ph/0412043},
year = {2009}
}
备注
10 pages, 2 figures, submitted on 2004 Oct. 20 and accepted on 2004 Dec. 1 for publication in ApJ Letters