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Many efforts have been made to model the mass distribution and dynamicalevolution of the circumnuclear gas in active galactic nuclei (AGNs). However,chemical evolution is not included in detail in three-dimensional (3-D)hydrodynamic simulations. The X-ray radiation from the AGN can drive the gaschemistry and affect the thermodynamics, as well as the excitation of theinterstellar medium (ISM). Therefore, we estimate the effects (on chemicalabundances and excitation) of X-ray irradiation by the AGN, for atomic andmolecular gas in a 3-D hydrodynamic model of an AGN torus. We obtain theabundances of various species from an X-ray chemical model. A 3-D radiativetransfer code estimates the level populations, which result in line intensitymaps. Predictions for the CO J=1-0 to J=9-8 lines indicate that mid-J CO linesare excellent probes of density and dynamics in the central (<60 pc) region ofthe AGN, in contrast to the low-J CO lines. Analysis of the X_CO/\alphaconversion factors shows that only the higher-J CO lines can be used for gasmass determination in AGN tori. The [C II] 158 um emission traces mostly thehot (T_k>1000m K) central (<60 pc) region of the AGN torus. The [C II] 158 umline will be useful for ALMA observations of high redshift (z>1) AGNs. Thespatial scales (>0.25 pc) probed with our simulations match the size of thestructures that ALMA will resolve in nearby (<45 Mpc at 0.01") galaxies.

The Structure and Dynamics of an AGN Torus: CO Line Predictions for ALMA from 3D Hydrodynamical Simulations with X-ray Driven Chemistry