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
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).
Create a lesson
Related papers
On binary pulsars and the force of gravity
Davor Palle
Tidal torques. A critical review of some techniques
Michael Efroimsky, James G. Williams
Dynamics of a Spherical Accretion Shock with Neutrino Heating and Alpha-Particle Recombination
Rodrigo Fernández, Christopher Thompson
Asymptotically FRW black holes
J. T. Firouzjaee, Reza Mansouri
Reaction of Accretion Disks to Abrupt Mass Loss During Binary Black Hole Merger
Sean M. O'Neill, M. Coleman Miller, Tamara Bogdanovic et al.
A Gamma-Ray Burst/Pulsar for Cosmic-Ray Positrons with a Dark Matter-like Spectrum
Kunihito Ioka