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The accretion rates needed to fuel the central black hole in a galaxy can beachieved via viscous torques in thick disks and rings, which can be resolved bymillimetre interferometry within the inner ~20pc of the active galaxy NGC1068at comparable scales and sensitivity to single dish observations of theCircumnuclear Disk (CND) in the Galactic Center. To interpret observations ofthese regions and determine the physical properties of their gas distribution,we present a modelling effort that includes (i) a simple dynamical simulationsinvolving partially inelastic collisions between disk gas clouds, (ii) ananalytical model of a turbulent clumpy gas disk calibrated by the dynamicalmodel and observations, (iii) local turbulent and cosmic ray gas heating andcooling via H2O, H2, and CO emission, and (iv) determination of the molecularabundances. We also consider photodissociation regions (PDR) where gas isdirectly illuminated by the central engine. We compare the resulting modeldatacubes of the CO, HCN, HCO+, and CS brightness temperatures to availableobservations. In both cases the kinematics can be explained by one or twoclouds colliding with a pre-existing ring, in a prograde sense for the CND andretrograde for NGC1068. And, with only dense disk clouds, the line fluxes canbe reproduced to within a factor of about two. To avoid self-absorption of theintercloud medium, turbulent heating at the largest scales, comparable to thedisk height, has to be decreased by a factor of 50-200. Our models indicatethat turbulent mechanical energy input is the dominant gas heating mechanismwithin the thick gas disks. In N1068, while the bulk of the AGN X-ray radiationis absorbed in a layer of Compton-thick gas inside the dust sublimation radius,the optical/UV radiation may enhance the molecular line emission fromphotodissociation regions by ~50% at the inner edge of the gas ring.

astronomy and astrophysics

From the Circumnuclear Disk in the Galactic Center to thick, obscuring  tori of AGNs -- Modelling the molecular emission of a parsec-scale torus as  found in NGC1068