2003ApJ...598..886U -
Astrophys. J., 598, 886-908 (2003/December-1)
Cosmological evolution of the hard X-ray active galactic nucleus luminosity function and the origin of the hard X-ray background.
UEDA Y., AKIYAMA M., OHTA K. and MIYAJI T.
Abstract (from CDS):
We investigate the cosmological evolution of the hard X-ray luminosity function (HXLF) of active galactic nuclei (AGNs) in the 2-10 keV luminosity range of 1041.5-1046.5 ergs/s as a function of redshift up to 3. From a combination of surveys conducted at photon energies above 2 keV with HEAO 1, ASCA, and Chandra, we construct a highly complete (>96%) sample consisting of 247 AGNs over the wide flux range of 10–10 to 3.8x10–15 ergs/cm2/s (2-10 keV). For our purpose, we develop an extensive method of calculating the intrinsic (before absorption) HXLF and the absorption (NH) function. This utilizes the maximum likelihood method, fully correcting for observational biases with consideration of the X-ray spectrum of each source. We find that (1) the fraction of X-ray absorbed AGNs decreases with the intrinsic luminosity and (2) the evolution of the HXLF of all AGNs (including both type I and type II AGNs) is best described with a luminosity-dependent density evolution (LDDE) where the cutoff redshift increases with the luminosity. Our results directly constrain the evolution of AGNs that produce a major part of the hard X-ray background, thus solving its origin quantitatively. A combination of the HXLF and the NHfunction enables us to construct a purely ``observation-based'' population synthesis model. We present basic consequences of this model and discuss the contribution of Compton-thick AGNs to the rest of the hard X-ray background.
Abstract Copyright:
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Journal keyword(s):
Cosmology: Diffuse Radiation - Galaxies: Active - Galaxies: Quasars: General - Surveys - X-Rays: Diffuse Background
CDS comments:
H 1443+421, PSPC 504, and HRI 307 not identified
Simbad objects:
24
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