Mg II lambda 2798 emission in QSOs, Seyfert 1 galaxies, and broad-line radio galaxies.
Abstract
Spectrophotometric observations of Mg ii A2798 and Hfl emission in 14 QSOs, four Seyfert 1 galaxies, and two broad-line radio galaxies are presented. Both broad and narrow components of Mg ii A2798 are found to occur. In most cases the profiles of the broad components of Mg ii and Hfl are observed to be virtually identical, suggesting that these lines arise from the same optically thick emission clouds, and that these clouds have the same average Mg ii/Hfl ratio. In five objects, however, the Mg ii A2798 line is significantly broader than Hfl. The Mg ii/Hfl ratio in the broad components is generally observed to range from roughly 0.5 to 2.5, thus apparently ruling out emission-line clouds with huge transition zones. Either internal dust or radiatively accelerated clouds might explain the truncated transition regions. Narrow Mg ii A2798 emission is found to be surprisingly weak in comparison with other narrow lines such as [0 ii] A3727. It is suggested that the weakness of the narrow Mg ii emission may be related to the observed rareness of Mg ii A2798 absorption in QSOs near the emission-line redshift. Subject headings: galaxies: Seyfert - line profiles - quasars - radio sources: galaxies
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1979
- DOI:
- 10.1086/157324
- Bibcode:
- 1979ApJ...232..659G
- Keywords:
-
- Emission Spectra;
- Magnesium;
- Quasars;
- Radio Galaxies;
- Seyfert Galaxies;
- Ultraviolet Radiation;
- Astronomical Catalogs;
- Clouds;
- H Beta Line;
- Spectral Line Width;
- Spectrophotometry;
- Astrophysics;
- Magnesium:Quasars;
- Magnesium:Radio Galaxies;
- Magnesium:Seyfert Galaxies;
- Quasars:Spectrophotometry;
- Radio Galaxies:Spectrophotometry;
- Seyfert Galaxies:Spectrophotometry