ROSAT Hard-Spectrum X-Ray Source Catalog
This table contains a catalog of 147 serendipitous X-ray sources selected to have hard spectra (spectral indices Alpha < 0.5) from a survey of 188 ROSAT fields. Such sources must be the dominant contributors to the X-ray background at faint fluxes. The authors have used Monte Carlo simulations to verify that their technique is very efficient at selecting hard sources: the survey has >= 10 times as much effective area for hard sources as it has for soft sources above a 0.5 - 2 keV flux level of 10<sup>-14</sup> erg cm<sup>-2</sup> s<sup>-1</sup>. The distribution of best-fitting spectral slopes of the hard sources suggests that a typical ROSAT hard source in this survey has a spectral slope Alpha ~ 0. The hard sources have a steep number-flux relation (dN/dS ~ _S<sup>-Gamma</sup>, with a best-fitting value of Gamma = 2.72 +/- 0.12), and make up about 15% of all 0.5 - 2 keV sources with S > 10<sup>-14</sup> erg cm<sup>-2</sup> s<sup>-1</sup>. If their N(S) continues to fainter fluxes, the hard sources will comprise ~ 40% of sources with 5 x 10<sup>-15</sup> < S < 10<sup>-14</sup> erg cm<sup>-2</sup> s<sup>-1</sup>. The population of hard sources can therefore account for the harder average spectra of ROSAT sources with S < 10<sup>-14</sup>erg cm<sup>-2</sup> s<sup>-1</sup>. They probably make a strong contribution to the X-ray background at faint fluxes and could be the solution to the X-ray background spectral paradox. This table was created by the HEASARC in March 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/318/1073">CDS Catalog J/MNRAS/318/1073</a> file table2.dat, the ROSAT hard X-ray source catalog. This is a service provided by NASA HEASARC .
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| @type | dcat:Dataset |
|---|---|
| accessLevel | public |
| bureauCode |
[ "026:00" ] |
| contactPoint |
{ "fn": "HEASARC Help Desk", "@type": "vcard:Contact", "hasEmail": "mailto:andrew.ptak@nasa.gov" } |
| description | This table contains a catalog of 147 serendipitous X-ray sources selected to have hard spectra (spectral indices Alpha < 0.5) from a survey of 188 ROSAT fields. Such sources must be the dominant contributors to the X-ray background at faint fluxes. The authors have used Monte Carlo simulations to verify that their technique is very efficient at selecting hard sources: the survey has >= 10 times as much effective area for hard sources as it has for soft sources above a 0.5 - 2 keV flux level of 10<sup>-14</sup> erg cm<sup>-2</sup> s<sup>-1</sup>. The distribution of best-fitting spectral slopes of the hard sources suggests that a typical ROSAT hard source in this survey has a spectral slope Alpha ~ 0. The hard sources have a steep number-flux relation (dN/dS ~ _S<sup>-Gamma</sup>, with a best-fitting value of Gamma = 2.72 +/- 0.12), and make up about 15% of all 0.5 - 2 keV sources with S > 10<sup>-14</sup> erg cm<sup>-2</sup> s<sup>-1</sup>. If their N(S) continues to fainter fluxes, the hard sources will comprise ~ 40% of sources with 5 x 10<sup>-15</sup> < S < 10<sup>-14</sup> erg cm<sup>-2</sup> s<sup>-1</sup>. The population of hard sources can therefore account for the harder average spectra of ROSAT sources with S < 10<sup>-14</sup>erg cm<sup>-2</sup> s<sup>-1</sup>. They probably make a strong contribution to the X-ray background at faint fluxes and could be the solution to the X-ray background spectral paradox. This table was created by the HEASARC in March 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/318/1073">CDS Catalog J/MNRAS/318/1073</a> file table2.dat, the ROSAT hard X-ray source catalog. This is a service provided by NASA HEASARC . |
| distribution |
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| identifier | ivo://nasa.heasarc/rosathard |
| keyword |
[ "__" ] |
| landingPage | ivo://nasa.heasarc/rosathard |
| license | https://www.usa.gov/government-works |
| modified | 2026-10-27 |
| programCode |
[ "026:000" ] |
| publisher |
{ "name": "High Energy Astrophysics Science Archive Research Center", "@type": "org:Organization" } |
| theme |
[ "Astrophysics" ] |
| title | ROSAT Hard-Spectrum X-Ray Source Catalog |
