Stellar and Gaseous Kinematics in the Narrow Line Region of Seyfert Galaxies

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Session 30 -- Seyfert Galaxies
Oral presentation, Wednesday, January 12, 2:15-3:45, Salon IV Room (Crystal Gateway)

[30.02] Stellar and Gaseous Kinematics in the Narrow Line Region of Seyfert Galaxies

Charles H. Nelson, Mark Whittle (U. Va.)

The ionized gas kinematics in the narrow line region (NLR) of Seyfert galaxies are influenced by both the active nucleus and properties of the host galaxy. Recent studies have found that in most Seyferts forbidden line widths correlate well with bulge absolute magnitude, M$_{bul}$, and rotational velocity amplitude $\Delta$V$_{rot}$, parameters related to host gravitational potential. In galaxies with kpc-scale linear radio sources, interaction between the radio jets and NLR gas provides an additional line broadening mechanism associated with the active nucleus. However, M$_{bul}$ and $\Delta$V$_{rot}$ only indirectly characterize the host potential. We have obtained measurements of a direct virial parameter, the velocity dispersion, $\sigma_*$, from stellar absorption features (Ca triplet and/or Mg b) for a sample of $\sim$75 Seyferts. We have also measured widths of the [OIII] $\lambda$5007 \AA~ emission line. These data are used in conjunction with the Whittle (1992) compilation of NLR and host galaxy properties, to examine the relationship between the stellar and ionized gas kinematics and the role of the host gravitational potential in Seyfert galaxies.

Our results show that a good correlation exists between [OIII] FWHM and $\sigma_*$ demonstrating that the NLR line widths are largely produced by motion of gas in the host gravitational potential. As in the correlations with indirect virial parameters, objects with kpc scale linear radio sources fall off the correlation, having broader lines than expected on the basis of purely virial motion. Some of the remaining scatter in this correlation appears to be associated with morphological disturbance due to galaxy interaction. A strong correlation between M$_{bul}$ and $\sigma_*$ exists for Seyferts, but is offset from the Faber-Jackson relation for normal galaxies in the sense of lower M/L. This may indicate higher star formation rates for Seyferts in the recent past. The radio and [OIII] luminosity also correlate with $\sigma_*$, suggesting a link between the active properties and the gravitational potential.

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