We present optical spectroscopic identification of sources identified in the BeppoSAX MECS fields of the High Energy LLarge Area Survey (HELLAS). In total 62 sources from a sample of 115 brighter than F_{5-10keV}>5x10^{-14} cgs have been identified. We find a density of 13-21 sources/deg^2 at F_{5-10keV}>5x10^{-14} cgs, which contribute to 20-30 % of the hard X-ray background. Evidences are found for type 1 AGN being more absorbed with increasing redshift or luminosity. The low redshift (z<0.2) ratio of type 2 to type 1 AGN is 3+/-1.5, in agreement with the unified models for AGN. The luminosity function of type 1 AGN in the 2-10 keV band is preliminary fitted by a two-power law function evolving according to a pure luminosity evolution model: L~(1+z)^{2.2}.

LA FRANCA, F., Fiore, F., Vignali, C., Comastri, A., Pompilo, F., the HELLAS, C. (2001). The Evolution of AGN in the Hard X-rays from HELLAS. In The New Era of Wide Field Astronomy (pp.96). S. FRANCISCO : ASP Conference Series.

The Evolution of AGN in the Hard X-rays from HELLAS

LA FRANCA, Fabio;
2001-01-01

Abstract

We present optical spectroscopic identification of sources identified in the BeppoSAX MECS fields of the High Energy LLarge Area Survey (HELLAS). In total 62 sources from a sample of 115 brighter than F_{5-10keV}>5x10^{-14} cgs have been identified. We find a density of 13-21 sources/deg^2 at F_{5-10keV}>5x10^{-14} cgs, which contribute to 20-30 % of the hard X-ray background. Evidences are found for type 1 AGN being more absorbed with increasing redshift or luminosity. The low redshift (z<0.2) ratio of type 2 to type 1 AGN is 3+/-1.5, in agreement with the unified models for AGN. The luminosity function of type 1 AGN in the 2-10 keV band is preliminary fitted by a two-power law function evolving according to a pure luminosity evolution model: L~(1+z)^{2.2}.
2001
1-58381-065-X
LA FRANCA, F., Fiore, F., Vignali, C., Comastri, A., Pompilo, F., the HELLAS, C. (2001). The Evolution of AGN in the Hard X-rays from HELLAS. In The New Era of Wide Field Astronomy (pp.96). S. FRANCISCO : ASP Conference Series.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11590/170667
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