The feeding of activity in galaxies: a molecular line perspective
  What are the main drivers of activity in the local universe? Observations
have been instrumental in identifying the mechanisms responsible for fueling
activity in galaxy nuclei. In this context we summarize the main results of the
NUclei of GAlaxies (NUGA) survey. The aim of NUGA is to map, at high resolution
and high sensitivity, the distribution and dynamics of the molecular gas in the
central kiloparsec region of 25 galaxies, and to study the different mechanisms
responsible for gas fueling of low-luminosity AGNs (LLAGN). Gas flows in NUGA
maps reveal a wide range of instabilities. The derived gravity torque maps show
that only about 1/3 of NUGA galaxies show evidence of ongoing fueling. Secular
evolution and dynamical decoupling are seen to be key ingredients to understand
the AGN fueling cycle. We discuss the future prospects for this research field
with the advent of instruments like the Atacama Large Millimeter Array (ALMA).
