Quasar H-beta profiles and discs.

Abstract

We present high signal-to-noise spectra of the Hβ region of eight radio-loud quasars in an investigation seeking evidence for the emission of this line from a disc. Although we do not find the double-humped profile expected in simple versions of the disc hypothesis, we do find shoulders in the profile expected in a modified form of this idea. A model in which the radiation is scattered back from above the disc plane can reproduce the observed spectra provided that the disc is sufficiently large. We discuss whether this model can explain why other Hβ profiles are shoulderless, and whether it is consistent with variability data.