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26 April 2024 |
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The BeppoSAX High Energy Large Area Survey HELLAS, II: Number counts and X-ray spectral properties | | F. Fiore
; P. Giommi
; C. Vignali
; A. Comastri
; G. Matt
; G.C. Perola
; F. La Franca
; S. Molendi
; F. Tamburelli
; L.A. Antonelli
; | | Date: |
30 May 2001 | | Journal: | Mon.Not.Roy.Astron.Soc. 327 (2001) 771 | | Subject: | astro-ph | | 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. | | Source: | arXiv, astro-ph/0105524 | | Services: | Forum | Review | PDF | Favorites | |
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