Active galactic nuclei and star-forming galaxies - contributing to the extragalactic X-ray flux.
Abstract
The nature of discrete sources contributing to the extragalactic `X-ray background' (XRB) in the energy range ~0.1-3 keV has been investigated via optical identifications based on positional coincidence and spectroscopy. The results presented here address the counterparts to the discrete X-ray sources detected in the Einstein Observatory deep X-ray survey in Pavo. X-ray selected quasars, detected to a limiting flux of ~10^-14^ erg cm^-2^ s^-1^ and a limiting B_j_ magnitude of 21.5, have a surface density of ~32 per square degree, an average redshift of 0.94, and account directly for ~15 per cent of the extragalactic X-ray background at an effective energy of 2 keV. Other discrete-source detections in the Pavo survey have included the discovery of the first examples of star-forming (narrow emission line) galaxies at moderate redshift, of the kind which may contribute substantially to the XRB in the energy range ~3-20 keV. One further object is an elliptical (cD) galaxy in a cluster with X-ray emission possibly arising from a cooling flow.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 1992
- DOI:
- 10.1093/mnras/255.4.545
- Bibcode:
- 1992MNRAS.255..545G
- Keywords:
-
- Active Galactic Nuclei;
- Extraterrestrial Radiation;
- Star Formation;
- X Ray Astronomy;
- X Ray Sources;
- Astronomical Spectroscopy;
- Cooling Flows (Astrophysics);
- Cosmic Background Explorer Satellite;
- Elliptical Galaxies;
- Galactic Clusters;
- Radiant Flux Density;
- Red Shift;
- Astrophysics