Thick Disks, and an Outflow, of Dense Gas in the Nuclei of Nearby
  Seyfert Galaxies
  We discuss the dense molecular gas in central regions of nearby Seyfert
galaxies, and report new arcsec resolution observations of HCN(1-0) and
HCO$^+$(1-0) for 3 objects. In NGC 3079 the lines show complex profiles as a
result of self-absorption and saturated continuum absorption. H$^{13}$CN
reveals the continuum absorption profile, with a peak close to the galaxy's
systemic velocity that traces disk rotation, and a second feature with a blue
wing extending to $-350$km s$^{-1}$ that most likely traces a nuclear outflow.
The morphological and spectral properties of the emission lines allow us to
constrain the dense gas dynamics. We combine our kinematic analysis for these 3
objects, as well as another with archival data, with a previous comparable
analysis of 4 other objects, to create a sample of 8 Seyferts. In 7 of these,
the emission line kinematics imply thick disk structures on radial scales of
$\sim$100pc, suggesting such structures are a common occurrence. We find a
relation between the circumnuclear LHCN and Mdyn that can be explained by a gas
fraction of 10% and a conversion factor {\alpha}HCN $\sim$ 10 between gas mass
and HCN luminosity. Finally, adopting a different perspective to probe the
physical properties of the gas around AGN, we report on an analysis of
molecular line ratios which indicates that the clouds in this region are not
self-gravitating.
