The Link between Galaxy Disturbance and Emission Line Width in Seyfert Galaxies (Poster paper)

Summary

ABSTRACT

We have measured or compiled stellar velocity dispersions, σ_*, for a sample of ∼ 80 Seyfert galaxies. The [OIII] λ5007Å emission line width correlates quite strongly with σ_*, suggesting ionized gas velocities result principally from motion in the host bulge potential. Here we concentrate on second order effects, looking for parameters which correlate with the scatter on the [OIII] FWHM vs. σ_* relation. In decreasing order of clarity, we find that Seyferts with relatively broad emission lines (e.g. V_gas > V_stars) have strong linear radio sources, are disturbed, or have bars. Since these galaxies show no unusual scatter on the Faber-Jackson plot of σ_* vs M_bul, we conclude that radio luminous Seyferts and tidally disturbed Seyferts have unusual gas kinematics rather than unusual stellar kinematics.

The profiles of forbidden emission lines characterize the ionized gas kinematics in the Narrow Line Region (NLR) of Seyfert galaxies. What physical processes accelerate this gas, and are they related to the active nucleus or to the host galaxy? To explore the role of the host galaxy, we have measured stellar velocity dispersions, σ_*, for 78 objects using the cross-correlation method. We also include published measurements of σ_* (e.g. Terlevich, Dias, and Terlevich 1990; Whitmore et al. 1985) and complementary data on NLR and host properites, from Whittle (1992). In particular, we include the Perturbation Class, PC, which rates the degree of galaxy disturbance and/or interaction on a scale of 1 to 6 (based on the scheme of Dahari [1985]).