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We have mapped the central region of NGC 4945 in the $J=2\to1$ transition of$^{12}$CO, $^{13}$CO, and C$^{18}$O, as well as the continuum at 1.3 mm, at anangular resolution of $5\farc \times 3\farc$ with the Submillimeter Array. Therelative proximity of NGC 4945 (distance of only 3.8 Mpc) permits a detailedstudy of the circumnuclear molecular gas and dust in a galaxy exhibiting bothan AGN (classified as a Seyfert 2) and a circumnuclear starburst in an inclinedring with radius $\sim$2\farcs5 ($\sim$50 pc). We find that all three molecularlines trace an inclined rotating disk with major axis aligned with that of thestarburst ring and large-scale galactic disk, and which exhibits solid-bodyrotation within a radius of $\sim$5\farc ($\sim$95 pc). We infer an inclinationfor the nuclear disk of $62^{\circ} \pm 2^{\circ}$, somewhat smaller than theinclination of the large-scale galactic disk of $\sim$$78^{\circ}$. Thecontinuum emission at 1.3 mm also extends beyond the starburst ring, and isdominated by thermal emission from dust. If it traces the same dust emitting inthe far-infrared, then the bulk of this dust must be heated by star-formationactivity rather than the AGN. We discover a kinematically-decoupled componentat the center of the disk with a radius smaller than $1\farcs4$ (27 pc), butwhich spans approximately the same range of velocities as the surrounding disk.This component has a higher density than its surroundings, and is a promisingcandidate for the circumnuclear molecular torus invoked by AGN unificationmodels.

The Circumnuclear Molecular Gas in the Seyfert Galaxy NGC4945