Consistency of accretion discs with Seyfert 1 UV fluxes and Hβ emission-line profiles

Abstract

This paper presents accretion disc fits to the UV continuum and Hβ emission line in a complete sample of broad-emission-line AGN sources. Disc fits to the UV continuum emission leave an ambiguity between the central mass and the orientation of the disc in that more massive black holes mimic more edge-on discs. The opposite dependence between mass and orientation is derived from disc fits to the broad-line profile. Fitting both continuum shape and line profile consistently can thus lead to a unique determination of the two parameters. Models consistent with the two emission components have a low inclination (with means equal to ~25 deg and 35 deg for extreme Kerr and Schwarzschild black holes respectively), supporting orientation-dependent unification schemes. The derived masses confirm the non-linearity between mass and luminosity for AGN, and rule out a pure luminosity evolution of distant quasars to nearby Seyfert 1 nuclei. Finally, the disc irradiation and the size of the Hβ emission region are estimated.