The evolution of AGN in the Hard X-rays from HELLAS
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}.
Cite
@article{arxiv.astro-ph/0011008,
title = {The evolution of AGN in the Hard X-rays from HELLAS},
author = {F. La Franca and F. Fiore and C. Vignali and A. Comastri and F. Pompilio and HELLAS consortium},
journal= {arXiv preprint arXiv:astro-ph/0011008},
year = {2007}
}
Comments
6 pages and 4 ps figures. To be published in Proc. of the Conference "the New Era of Wide-Field Astronomy", held in Preston (UK), 21-24 August 2000