The BeppoSAX High Energy Large Area Survey HELLAS, II: Number counts and X-ray spectral properties
Abstract
The BeppoSAX High Energy Large Area Survey (HELLAS) has surveyed about 85 deg2 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 alphaE = 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.
Turn this paper into a full lesson
ArcXiv compiles a staged curriculum from this paper: 8-12 lessons across beginner → advanced, synthesised section guides, visuals, flashcards, a quiz, exercises, and on-demand deep dives per section. Grounded in the abstract, never invented.