X-ray background and discrete, evolving sources
Abstract
The contributions of discrete, evolving, extragalactic X-ray sources to the X-ray background are investigated on the basis of data from the Einstein Observatory deep survey and optical and X-ray studies of catalogued quasars. Comparisons of the deep survey data and studies of the correlations of the X-ray and optical quasar fluxes are shown to imply that the average two-point energy index that determines the relative luminosities of sources at given optical and X-ray frequencies must be larger than 1.5 for sources evolving like quasars. This result can be explained by the catalogued quasars being fainter at 2 keV than previously estimated, or by a difference in the X-ray properties of radio-loud and radio-quiet quasars. In either case, it is concluded that any major contribution to the X-ray background associated with discrete evolving sources must come from objects very faint in both the optical and X-ray regions.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- May 1980
- Bibcode:
- 1980A&A....85L...9C
- Keywords:
-
- Background Radiation;
- Quasars;
- X Ray Astronomy;
- X Ray Sources;
- Astronomical Catalogs;
- Astronomical Observatories;
- Data Acquisition;
- Data Processing;
- Light (Visible Radiation);
- Luminous Intensity;
- Spectrum Analysis;
- Astrophysics