The stellar and nonstellar continua of Seyfert galaxies Nonthermal emission in the near-infrared

Abstract

Spectra having high resolution and excellent signal-to-noise ratios have been obtained for the nuclei of nine Seyfert galaxies. In Seyfert 1 nuclei the Mg I λ5175, Na I D λ5892, and Ca II λ8542 stellar absorption lines are extremely weak, indicating that galactic starlight does not contribute a significant fraction of the observed continuum. The relative amount of light (in a given aperture) due to the unresolved nucleus of each galaxy has been measured from direct images made with a silicon intensified target. The authors deduced the total stellar and nonstellar continuum fluxes in the spectral range λλ5000 - 8600. The starlight has colors which are typical of those in the disks of normal spiral galaxies. The nonstellar continuum is similar to that of quasars. Even at minimum brightness, the nonstellar flux has no short-wavelength cutoff near 1 μm.