The BeppoSAX High Energy Large Area Survey HELLAS, II: Number counts and X-ray spectral properties

Preprint

30 May 2001

preprint
Published by arXiv in arXiv

https://doi.org/10.48550/arXiv.astro-ph/0105524

Abstract

The BeppoSAX High Energy Large Area Survey (HELLAS) has surveyed about 85 deg^2 of sky in the 5-10 keV band down to a flux of 4-5 10^-14 erg cm-2 s-1. The source surface density of 16.9+-6.4 deg$^{-2}$ at the survey limit corresponds to a resolved fraction of the 5-10 keV X-ray background (XRB) of the order of 20-30 %. Hardness ratios analysis indicates that the spectra of a substantial fraction of the HELLAS sources (at least one third) are harder than a alpha_E = 0.6 power law. This hardness may be due to large absorbing columns. The hardness ratio analysis also indicates that many HELLAS sources may have a spectrum more complex than a single absorbed power law. A soft component, superimposed to a strongly cut-off power law, is likely to be present in several sources.

Keywords

All Related Versions

Version 1, 2001-05-30, ArXiv
Published version: Monthly Notices of the Royal Astronomical Society, 327 (3), 771.

This publication has 0 references indexed in Scilit: