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Date and Time of the Query: 2019-08-20 T23:11:08 PDT
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For refcode 2010ApJ...720L.206Z:
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Copyright by American Astronomical Society. Reproduced by permission
2010ApJ...720L.206Z Hard X-ray Photon Index as an Indicator of Bolometric Correction in Active Galactic Nuclei Zhou, Xin-Lin; Zhao, Yong-Heng Abstract. We propose the rest-frame 2-10 keV photon index, Gamma_2-10 keV_, acting as an indicator of the bolometric correction, L_bol_/L_2-10 keV_ (where L_bol_ is the bolometric luminosity and L_2-10 keV_ is the rest-frame 2-10 keV luminosity), in radio-quiet active galactic nuclei (AGNs). Correlations between Gamma_2-10 keV_ and both bolometric correction and Eddington ratio are presented, based on simultaneous X-ray, UV, and optical observations of reverberation-mapped AGNs. These correlations can be compared with those for high-redshift AGNs to check for any evolutionary effect. Assuming no evolutionary effect in AGNs' spectral properties, together with the independent estimates of L_2-10 keV_, the bolometric correction, Eddington ratio, and black hole (BH) mass can all be estimated from these correlations for high-redshift AGNs, with the mean uncertainty of a factor of 2-3. If there are independent estimates of BH masses, Gamma_2-10 keV_ for high-redshift AGNs can be used to determine their true L_bol_ and L_2-10 keV_, and in conjunction with the redshift can be potentially used to place constraints on cosmology by comparison with the rest-frame 2-10 keV flux. We find that the true L_2-10 keV_ estimated from Gamma_2-10 keV_ for the brightest Type I AGNs with z < 1 in the Lockman Hole is generally in agreement with the observed L_2-10 keV_. However, there are still many uncertainties, such as the accurate determination of the intrinsic Gamma_2-10 keV_ for distant AGNs and the large uncertainty in the luminosities obtained, which call for significant further study before "AGN cosmology" can be considered a viable technique. Key words: black hole physics, cosmology: observations, galaxies: distances and redshifts, X-rays: diffuse background
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