Gas Dynamics in AGN Galaxies: First Results of the HI-NUGA Survey

Active Galactic Nuclei (AGN) galaxies are generally known as very luminous galaxies where a small emitting region is associated with gas accretion onto a central supermassive black hole. Up to now the process of fueling the AGN with material (gas or stars) generally far away from the gravitational influence of the central black hole is controversial and not understood. Since the required material has to remove its high angular momentum in order to fall into the center, various mechanisms may play a role, including m = 2 perturbations (bars and spirals), m = 1 perturbations (spirals, warps, lopsidedness), tidal interactions between galaxies, and galaxy mergers. In order to study the gas transport from the outskirts to the centers of AGN galaxies, we are carrying out a key project, named NUGA (Nuclei of Galaxies), which is a high spectral and angular resolution CO and HI survey of low luminosity AGN in nearby galaxies (Seyferts, LINERs and transition objects). The complete dataset provides us with the unique opportunity to understand and ultimately model the whole disk kinematics on spatial scales ranging over several orders of magnitude. Here, we will present observations of 15 galaxies recently obtained in the 21 cm emission of neutral hydrogen using the Very Large Array. First results on the HI gas and velocity distribution of these galaxies are summarized and discussed. The derived properties, including the ratio of dynamical mass versus gas mass (+ stellar mass), will be presented and compared with the AGN activity types in order to search for possible dependences. Additionally, effects of satellites and tidal disturbances onto the HI disk as well as their correlation with AGN type and dynamical modes probed by CO (inner kpc) will be examined.