Empirical results from a study of active galactic nuclei.
Abstract
Spectrophotometric observations are presented for emission-line galaxies. When combined with previous Lick Observatory measurements, they are used to deduce criteria that allow the Seyfert 2 phenomena to be quantitatively isolated from the narrow-emission-line galaxies. These criteria are based on the finding that galaxies with forbidden line O III 5007 A/H-beta ratios lower than 3 have emission line widths that are usually considerably smaller than the widths in galaxies with forbidden line O III 5007 A/H-beta ratios greater than 3. In addition, large He II 4686 A/H-beta ratios are consistent with forbidden line O III 5007 A/H-beta ratios greater than 3. The physical conditions in the narrow-line regions of Seyfert 1 galaxies are compared with those in Seyfert 2 galaxies. Significant differences are found for the temperature-sensitive forbidden line O III ratio, and for the luminosity of Fe VII forbidden line 6087 A relative to the luminosity of the low-ionization forbidden lines.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1981
- DOI:
- 10.1086/159347
- Bibcode:
- 1981ApJ...250...55S
- Keywords:
-
- Active Galactic Nuclei;
- Emission Spectra;
- Forbidden Bands;
- Line Spectra;
- Seyfert Galaxies;
- Spectrophotometry;
- Interstellar Extinction;
- Luminosity;
- Red Shift;
- Spectrum Analysis;
- Tables (Data);
- Temperature Effects;
- Astrophysics