The BeppoSAX High Energy Large Area Survey (HELLAS)

F. Fiore; P. Giommi; F. La Franca; G. Matt; G. C. Perola; A. Comastri; S. Molendi; M. Elvis; I Gioia; F. Tamburelli; D. Ricci; F. Pompilio

arXiv · astro-ph/9811149

The BeppoSAX High Energy Large Area Survey (HELLAS)

F. Fiore·P. Giommi·F. La Franca·G. Matt·G. C. Perola·A. Comastri·S. Molendi·M. Elvis·I Gioia·F. Tamburelli·D. Ricci·F. Pompilio

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Abstract

We have surveyed about 50 deg-2 of sky in the largely unexplored 5-10 keV band using the BeppoSAX MECS instrument, finding 180 sources. After correction for the non uniform sky coverage we find about 18 sources deg-2 with F(5-10keV) >= 5E-14 cgs, and resolve 30-40 % of the hard 5-10 keV Cosmic X-ray Background (XRB). Optical identification of a first small sample of sources show that most (11 out of 14) are AGN. Six of these show evidence of absorption/extinction in X-ray/optical, thus providing support to the scenario in which the hard XRB is largely made by obscured AGN (Setti & Woltjer 1989, Comastri et al. 1995).

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F. Fiore, P. Giommi, F. La Franca, G. Matt, G. C. Perola, A. Comastri, S. Molendi, M. Elvis, I Gioia, F. Tamburelli, D. Ricci, F. Pompilio. 1998-11-10. The BeppoSAX High Energy Large Area Survey (HELLAS). https://arxiv.org/abs/astro-ph/9811149

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