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Constraints on the cosmological evolution of AGNs from X-ray data*

Published online by Cambridge University Press:  19 July 2016

L. Danese ,
G. De Zotti ,
G. Fasano  and
A. Franceschini
L. Danese
Affiliation:
Istituto di Astronomia, Vicolo dell'Osservatorio, 5, I-35122 Padova, Italy
G. De Zotti
Affiliation:
Istituto di Astronomia, Vicolo dell'Osservatorio, 5, I-35122 Padova, Italy
G. Fasano
Affiliation:
Istituto di Astronomia, Vicolo dell'Osservatorio, 5, I-35122 Padova, Italy
A. Franceschini
Affiliation:
Istituto di Astronomia, Vicolo dell'Osservatorio, 5, I-35122 Padova, Italy

Extract

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Both the soft (Maccacaro et al., 1982; Gioia et al., 1984; Giacconi et al., 1979; Griffiths et al., 1983) and the hard (Piccinotti et al., 1982) X-ray surveys provide crucial information on the evolution of AGNs in the X-ray band. Before combining the two data sets, however, the consistency of the two flux scales must be checked. To this end we have compared the soft (SX) and the hard (HX) X-ray luminosities of all powerful (log(SX)>43.5) AGNs for which both IPC and hard X-ray fluxes are available in the literature (lower luminosity objects frequently exhibit large intrinsic, luminosity dependent, absorbing columns which cannot be accurately accounted for). We find <log(HX)/(SX)> = 0.17±0.06, to be compared with the expected value <log(HX)/(SX)>≃0 for a typical X-ray energy index αX≃0.7. Thus, an average correction factor of ≃1.5 needs to be applied to the IPC fluxes to bring them into the hard X-ray flux scale.

Type
V. Cosmological Studies, Clustering, Isotropy etc
Information
Symposium - International Astronomical Union , Volume 119: Quasars , 1986 , pp. 489 - 490
Copyright
Copyright © Reidel 1986 

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