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Discrete x-ray sources and the x-ray background
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Giacconi, Riccardo |
| Copyright Year | 1987 |
| Description | Since the discovery of a highly uniform X-ray background (XRB) in the 2 to 10 keV range, its nature is not yet fully explained. It appears clear from the results of Einstein medium and deep surveys that at least 50% of the XRB is due to individual extragalactic sources when their contribution is integrated to Z = 3. This includes contribution from Quasi Stellar Objects (QSOs), Active Galactic Nuclei (AGNs), galaxies, and clusters of galaxies. The average spectrum of each of the individual contributing sources is softer than that of the observed XRB. Therefore, the remaining contribution must have a rather hard spectrum of alpha nearly equal to 0.0 to 0.2. It is unlikely that this spectrum can be produced by diffuse processes. Therefore, the remainder of the XRB must be due to individual sources with the appropriate spectrum. This requires either that the spectrum of the already identified sources changes at early epochs or a new class of objects. Advanced X-ray Astrophysics Facility (AXAF) observations will extend survey sensitivity to limiting fluxes of order of 3 x 10 to the minus 16 erg/sq cm/s, some 50 times fainter than any previous survey. There will be sufficient sensitivity and angular resolution to permit identification and study of these objects. |
| File Size | 696658 |
| Page Count | 22 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19870014828 |
| Archival Resource Key | ark:/13960/t6xw99n6b |
| Language | English |
| Publisher Date | 1987-06-01 |
| Access Restriction | Open |
| Subject Keyword | Space Radiation Quasars Active Galactic Nuclei Thermal Emission Energy Spectra Heao 1 Uhuru Satellite Extragalactic Radio Sources X Ray Astronomy X Ray Astrophysics Facility Galactic Nuclei X Ray Sources Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
