ALMA observations of molecular tori around massive black holes
  We report ALMA observations of CO(3-2) emission in a sample of 7
Seyfert/LINER galaxies at the unprecedented spatial resolution of 0.1'' = 4-9
pc. Our aim is to explore the close environment of AGN, and the dynamical
structures leading to its fueling. The selected galaxies host low-luminosity
AGN, and have a wide range of activity types, and barred or ringed
morphologies. The observed maps reveal the existence of circum-nuclear disk
structures, defined by their morphology and decoupled kinematics. We call these
structures "molecular tori", even though they appear often as disks, without
holes in the center. They have varied orientations, unaligned with their host
galaxy. The radius of the tori ranges from 6 to 27 pc, and their mass from 0.7
10$^7$ to 3.9 10$^7$ Msun. At larger scale, the gas is always piled up in a few
100~pc scale resonant rings, that play the role of a reservoir to fuel the
nucleus. In some cases, a trailing spiral is observed inside the ring,
providing evidence for feeding processes. Most frequently, the torus and the
AGN are slightly off-centered, with respect to the bar-resonant ring position,
implying that the black hole is wandering by a few 10~pc amplitude around the
center of mass of the galaxy. Our spatial resolution allows us to measure gas
velocities inside the sphere of influence of the central black holes. By
fitting the observations with different simulated cubes, varying the torus
inclination and the black hole mass, it is possible to estimate the mass of the
central black hole, which is in general difficult for such late-type galaxies,
with only a pseudo-bulge.
