The redshift distribution of X-ray selected quasars - Is it really anomalous
Abstract
X-ray selected active galactic nuclei have a redshift distribution which is significantly different from that of optically selected quasars with the same optical magnitude. In particular, a much higher percentage of low-redshift quasars is found in the X-ray selected samples. However, it is shown in this paper that no qualitative difference in the X-ray properties of X-ray selected and optically selected quasars is required in order to explain the deficiency of high-redshift quasars in the available samples of X-ray selected objects. In fact, the redshift distribution of such samples is well reproduced by using evolutionary models and the optical luminosity function derived from optically selected samples plus the correlation between X-ray and optical luminosities found in a large sample of optically selected active galactic nuclei.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1982
- DOI:
- Bibcode:
- 1982ApJ...260L..31Z
- Keywords:
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- Galactic Nuclei;
- Luminosity;
- Quasars;
- Red Shift;
- X Ray Sources;
- Active Galactic Nuclei;
- Galactic Evolution;
- Heao 2;
- Seyfert Galaxies;
- Astrophysics