The luminosity function of Seyfert 1 galaxy nuclei and BL Lac objects, and the X-ray background.
Abstract
Summary. We have built the luminosity function of Seyfert 1 and BL Lac object nuclei. The main results of this study are that a) The luminosity function of Seyfert 1 nuclei is steep, which implies a rather large volume density of such nuclei fainter than Mv = -18 (using H0 = 50km s-1/Mpc); b) The volume density of BL Lac nuclei in the range - 23 < My < -21 is at least as large as that of the Seyfert 1 nuclei. A consequence of this fact is probably that BL Lac nuclei suffer a smaller cosmological evolution than do the Seyfert 1 nuclei (or quasars), as suspected by Setti and Woltjer (1977), as the surface density of faint BL LAC objects is much smaller than that of quasars. c) If the steep luminosity function of the Seyfert 1 nuclei extends to My = -16.5, these objects may easily account for most of the X-ray background in the range 2 to 10 keV. A high-sensitivity X-ray survey is probably the easiest way to detect these low-luminosity nuclei. Key words: Seyfert 1 galaxies - BL Lac objects - X-ray background
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- September 1979
- Bibcode:
- 1979A&A....78...46V
- Keywords:
-
- Bl Lacertae Objects;
- Galactic Nuclei;
- Luminous Intensity;
- Seyfert Galaxies;
- Astronomical Catalogs;
- Background Radiation;
- Ubv Spectra;
- X Ray Sources;
- Astrophysics;
- BL Lacertae Objects:Luminosity Function;
- Galactic Nuclei:Luminosity Function;
- Seyfert Galaxies:Nuclei;
- X-Ray Background