STELLAR AND GASEOUS KINEMATICS OF SEYFERT-GALAXIES .2. THE ROLE OF THE BULGE

We have used measurements of the nuclear stellar velocity dispersion, sigma, for a large sample of Seyfert galaxies to investigate the role played by the nuclear gravitational potential in defining the propert ies of active galaxies. We address four basic questions. First, do Sey ferts have unusual nuclear stellar dynamical properties compared to th ose of normal galaxies? Second, what are the relative contributions of gravitational and nongravitational forces creating the velocity field of the nuclear emission-line gas? Third, how do the emission-line and radio luminosities in the narrow-line region (NLR) depend on the bulg e potential? Fourth, in what way are the properties of Seyfert galaxie s related to those of radio galaxies? We find that Seyferts define a t ight correlation between sigma, and bulge absolute magnitude, similar to the Faber-Jackson relation for normal spiral bulges. We infer from this that Seyfert bulges are kinematically normal. The Seyfert relati on is, however, offset to higher bulge luminosities, which we interpre t as evidence for a lower mean mass-to-light ratio. Either Seyferts ha ve experienced higher than average star formation or they avoid system s with older stellar populations. We analyze the relations between sig ma and both galaxy rotation and galaxy absolute magnitude, finding si milar relations to those of normal spirals. This also supports a norma l kinematic relation between bulges and disks in Seyferts. A moderatel y strong correlation between sigma and [O III] profile width suggests that gravitational motion plays an important role in the NLR velocity held. The correlation is weaker with [O III] base and wing widths, al though the interpretation of this is not yet clear. The remaining real scatter on the relations indicates the importance of other factors. I n particular, objects with kiloparsec-scale linear radio sources can h ave significantly broader [O III] lines, confirming that interaction w ith an expanding radio source can accelerate the NLR gas. We also find that Seyferts that are tidally distorted have broader [O III] lines. The kinematic relations do not depend on galaxy inclination or Seyfert class, suggesting that the NLR gas is confined neither to the plane o f the galaxy nor to the plane of an inner obscuring disk. We find mode rately strong correlations between [O III] luminosity and sigma and b etween radio luminosity and sigma, confirming the importance of the b ulge potential in determining the overall NLR luminosity. More massive bulges may have more massive black holes, provide more fuel through s tellar mass loss, allow larger emitting regions, and/or have higher pr essures and emissivities. We included radio galaxies in our analysis o f the correlation between radio luminosity and bulge mass. Using total radio luminosity, the radio galaxies and Seyferts show little connect ion. However, when the core luminosities of radio galaxies are used, t he two groups form a single continuous steep relation spanning 6 mag i n M(bul). There is some evidence that at a given bulge mass, more ''je tlike'' sources (Seyferts with linear morphology, and cores of FR II r adio galaxies) are more luminous than the less ''jetlike'' sources (Se yferts without linear morphology, and cores of FR I radio galaxies). F inally, the radio galaxies fall on the same Faber-Jackson relation as the Seyferts, offset from the normal galaxy relation. Thus, we see bot h unity and continuity between the properties of Seyfert galaxies and radio galaxies. In particular, we can understand the separation of rad io-quiet and radio-loud objects into spirals and ellipticals as a dire ct manifestation of a more fundamental dependence of galactic scale ra dio luminosity on bulge mass.