The ultraviolet excess of Seyfert 1 galaxies and quasars

Citations Over TimeTop 1% of 1982 papers

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.

Related Papers

• → The emission-line regions in broad absorption line quasars(1986)49 cited
• → A spectroscopic analysis of the eclipsing nova-like EC 21178−5417 – discovery of spiral density structures(2020)5 cited
• → The spectrum of the T Tauri star Lk H 120(1977)7 cited
• → Variability of emission lines in quasar spectra(1986)2 cited
• → Quasars and Active Galactic Nuclei(2002)