skip to main content

Title: A JOINT MODEL OF X-RAY AND INFRARED BACKGROUNDS. II. COMPTON-THICK ACTIVE GALACTIC NUCLEUS ABUNDANCE

We estimate the abundance of Compton-thick (CT) active galactic nuclei (AGNs) based on our joint model of X-ray and infrared backgrounds. At L{sub rest2-10{sub keV}} > 10{sup 42} erg s{sup –1}, the CT AGN density predicted by our model is a few ×10{sup –4} Mpc{sup –3} from z = 0 up to z = 3. CT AGNs with higher luminosity cuts (>10{sup 43}, 10{sup 44}, and 10{sup 45} erg s{sup –1}) peak at higher redshift and show a rapid increase in number density from z = 0 to z ∼ 2-3. The CT AGN to all AGN ratio appears to be low (2%-5%) at f{sub 2-10{sub keV}} > 10{sup –15} erg s{sup –1} cm{sup –2} but rises rapidly toward fainter flux levels. The CT AGNs account for ∼38% of the total accreted supermassive black hole mass and contribute ∼25% of the cosmic X-ray background spectrum at 20 keV. Our model predicts that the majority (90%) of luminous and bright CT AGNs (L{sub rest2-10keV} > 10{sup 44} erg s{sup –1} or f{sub 2-10{sub keV}} > 10{sup –15} erg s{sup –1} cm{sup –2}) have detectable hot dust 5-10 μm emission, which we associate with a dusty torus. The fraction drops for faintermore » objects, to around 30% at L{sub rest2-10{sub keV}} > 10{sup 42} erg s{sup –1} or f{sub 2-10{sub keV}} > 10{sup –17} erg s{sup –1} cm{sup –2}. Our model confirms that heavily obscured AGNs (N{sub H{sub I}} > 10{sup 23} cm{sup –2}) can be separated from unobscured and mildly obscured ones (N{sub H{sub I}} < 10{sup 23} cm{sup –2}) in the plane of observed frame X-ray hardness versus mid-IR/X-ray ratio.« less
Authors:
; ;  [1]
  1. Infrared Processing and Analysis Center, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125 (United States)
Publication Date:
OSTI Identifier:
22270699
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 777; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; BACKGROUND RADIATION; BLACK HOLES; COSMIC DUST; COSMIC PHOTONS; GALAXIES; GALAXY NUCLEI; HARDNESS; INFRARED RADIATION; KEV RANGE; LUMINOSITY; RED SHIFT; STAR ACCRETION; X RADIATION