Title: Comparing physical properties of two extreme dynamical environments: The centers and outskirts of nearby disk galaxies

Abstract: The centers of galaxies are extreme environments, characterized by strong tidal forces, rapid rotational timescales, high gas density and star formation rates. On the other hand, outskirts of spiral galaxies are low in gas densities and star formation rates. The key link connecting these two environments in disk galaxies is dynamics: driving mass flows from the outermost regions, filling their centers with fresh star-forming material. I will present both of these extreme environments. First, I present high resolution 2-4“ (75-150 pc) and high sensitivity observations at 2 and 3 mm covering the central 50“ (~1.9 kpc) of the nearby, gas-rich, very actively star-forming double-barred spiral galaxy NGC 6946 obtained with the IRAM Plateau de Bure Interferometer. In this work we studied dynamical features of the inner, small-scale bar of NGC 6946 and its effects on the emission of molecular lines. Together with ancillary data (from 8 additional galaxy centers), we investigate, for example, whether the HCN/HCO+ ratio can reflect AGN activity. In the second part of my talk, I present a 10 pointing mosaic JVLA observation of neutral atomic hydrogen (HI) towards M83 that we combined with single dish GBT observation. In this work, we analyzed the kinematics of the super-extended HI disk (5 times the optical radius), in particular, velocity fields, line widths and mass flow rate profiles. We further investigated outer disk mass flow rates and their role in fueling M83's center with fresh gas.