SIMBAD references

2009ApJ...707..778D - Astrophys. J., 707, 778-786 (2009/December-2)

Balancing the cosmic energy budget: the cosmic X-ray background, blazars, and the Compton thick active galactic nucleus fraction.


Abstract (from CDS):

At energies ≳2 keV, active galactic nuclei (AGNs) are the source of the cosmic X-ray background (CXB). For AGN population synthesis models to replicate the peak region of the CXB (∼30 keV), a highly obscured and therefore nearly invisible class of AGN, known as Compton thick (CT) AGN, must be assumed to contribute nearly a third of the CXB. In order to constrain the CT fraction of AGNs and the CT number density we consider several hard X-ray AGN luminosity functions and the contribution of blazars to the CXB. Following the unified scheme, the radio AGN luminosity function is relativistically beamed to create a radio blazar luminosity function. An average blazar spectral energy density model is created to transform radio luminosity to X-ray luminosity. We find the blazar contribution to the CXB to be 12% in the 0.5-2 keV band, 7.4% in the 2-10 keV band, 8.9% in the 15-55 keV band, and 100% in the MeV region. When blazars are included in CXB synthesis models, CT AGNs are predicted to be roughly one-third of obscured AGNs, in contrast to the prediction of one half if blazars are not considered. Our model implies a BL Lac X-ray duty cycle of ∼13%, consistent with the concept of intermittent jet activity in low power radio galaxies.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: jets - quasars: general - X-rays: diffuse background

CDS comments: In table 1: 2052-447 is a misprint for 2052-474 which is QSO B2052-474 in SIMBAD.

Simbad objects: 50

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