Open AccessOn the detectability of distant Compton‐thick obscured quasars
Author(s) -
Fabian A.C.,
Wilman R.J.,
Crawford C.S.
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05138.x
Subject(s) - physics , quasar , astrophysics , active galactic nucleus , redshift , astronomy , luminosity , galaxy , supermassive black hole , compton scattering , black hole (networking) , bulge , electron , nuclear physics , computer network , routing protocol , routing (electronic design automation) , computer science , link state routing protocol
Chandra and XMM–Newton have resolved the X‐ray background (XRB) into point sources. Many of the fainter sources are obscured active galactic nuclei (AGN) with column densities in the range of , some of which have quasar‐like luminosities. According to obscuration models, the XRB above 8 keV is dominated by emission from Compton‐thick AGN, with column densities exceeding . Here, we consider whether Compton‐thick quasars are detectable by Chandra and XMM–Newton by their direct (i.e. not scattered) X‐ray emission. Detectability is optimized if the objects individually have a high luminosity and high redshift, so that the direct emission has a significant flux in the observed band. Using a simple galaxy formation model incorporating accreting black holes, in which quasars build most of their mass in a Compton‐thick manner before expelling the obscuring matter, we predict that moderately deep 100‐ks Chandra and XMM–Newton exposures may contain a handful of detectable Compton‐thick quasars. Deep Ms or more Chandra images should contain distant, optically faint, Compton‐thick sources. In passing we show that radiation pressure can be as effective in expelling the obscuring gas as quasars winds, and yields a black hole mass proportional to the velocity dispersion of the host bulge to the fourth power.