The ultraviolet excess of Seyfert 1 galaxies and quasars.
Abstract
A sharp rise from 4000 to 3650 A in the excess flux was obtained when a power-law determined in the red and infrared was subtracted from IR-optical-UV composite spectra of eight Seyfert 1 galaxies and quasars to measure UV excess. The excess is produced by Balmer continuum emission which, relative to H-alpha, is greater than the prediction of Case B recombination by a factor of 1.5-2.5. An additional component from 5000 A to the far-UV was found when the spectra were fitted with combinations of power-law and hydrogen recombination continua. The component is well described by a blackbody at a single temperature ranging from 20,000 to 30,000 K. All of the observed spectra were producible with combinations of power-law, recombination and blackbody emission, and all of the objects in the sample were found to have a power-law component with a slope of -1.1 + or - 0.1.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1982
- DOI:
- 10.1086/159701
- Bibcode:
- 1982ApJ...254...22M
- Keywords:
-
- Balmer Series;
- Black Body Radiation;
- Galactic Radiation;
- Quasars;
- Seyfert Galaxies;
- Spectrophotometry;
- Ultraviolet Radiation;
- Galactic Nuclei;
- Interstellar Extinction;
- Paschen Series;
- Radiant Flux Density;
- Spectrum Analysis;
- Astrophysics