Molecular line emission in NGC1068 imaged with ALMA. I An AGN-driven
  outflow in the dense molecular gas
  We investigate the fueling and the feedback of star formation and nuclear
activity in NGC1068, a nearby (D=14Mpc) Seyfert 2 barred galaxy, by analyzing
the distribution and kinematics of the molecular gas in the disk. We have used
ALMA to map the emission of a set of dense molecular gas tracers (CO(3-2),
CO(6-5), HCN(4-3), HCO+(4-3) and CS(7-6)) and their underlying continuum
emission in the central r ~ 2kpc of NGC1068 with spatial resolutions ~
0.3"-0.5" (~ 20-35pc). Molecular line and dust continuum emissions are detected
from a r ~ 200pc off-centered circumnuclear disk (CND), from the
2.6kpc-diameter bar region, and from the r ~ 1.3kpc starburst (SB) ring. Most
of the emission in HCO+, HCN and CS stems from the CND. Molecular line ratios
show dramatic order-of-magnitude changes inside the CND that are correlated
with the UV/X-ray illumination by the AGN, betraying ongoing feedback. The gas
kinematics from r ~ 50pc out to r ~ 400pc reveal a massive (M_mol ~ 2.7 (+0.9,
-1.2) x 10^7 Msun) outflow in all molecular tracers. The tight correlation
between the ionized gas outflow, the radio jet and the occurrence of outward
motions in the disk suggests that the outflow is AGN-driven. The outflow rate
estimated in the CND, dM/dt ~ 63 (+21, -37) Msun yr^-1, is an order of
magnitude higher than the star formation rate at these radii, confirming that
the outflow is AGN-driven. The power of the AGN is able to account for the
estimated momentum and kinetic luminosity of the outflow. The CND mass load
rate of the CND outflow implies a very short gas depletion time scale of <=1
Myr.
