Inner Shell of Optically Thin Gas in Active Galactic Nuclei

Abstract

The Lyα and Balmer line profiles in more than 50 Seyfert 1 galaxies and QSOs are studied. Approximately 60% of the objects show similar profiles, 25% show smaller FWHM of Hβ or Hα. In five objects the Lyα profiles have stronger wings than the Balmer lines. The Lyα/Balmer ratio increases along both wings, suggesting an inner envelope of a very broad-line region. This region accounts for up to 10% of the total Balmer line emission and 50% of the Lyα emission. The far wings are often fitted with a power-law curve better than logarithmic. The optically thin gas in these objects is in Keplerian motion, and therefore is accreted rather than ejected.