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 100 pc , suggesting such structures are a common occurrence .
We find a relation between the circumnuclear L _ { HCN } and M _ { dyn } 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 .