We have mapped the central region of NGC 4945 in the J = 2 \rightarrow 1 transition of ^ { 12 } CO , ^ { 13 } CO , and C ^ { 18 } O , as well as the continuum at 1.3 mm , at an angular resolution of 5 \hbox { $ { } ^ { \prime \prime } $ } \times 3 \hbox { $ { } ^ { \prime \prime } $ } with the Submillimeter Array .
The relative proximity of NGC 4945 ( distance of only 3.8 Mpc ) permits a detailed study of the circumnuclear molecular gas and dust in a galaxy exhibiting both an AGN ( classified as a Seyfert 2 ) and a circumnuclear starburst in an inclined ring with radius \sim 2 . ^ { \prime \prime } 5 ( \sim 50 pc ) .
We infer the systemic velocity \sim 585 { km s ^ { -1 } } from channel maps and PV-diagrams .
We find that all three molecular lines trace an inclined rotating disk with major axis aligned with that of the starburst ring and large-scale galactic disk , and which exhibits solid-body rotation within a radius of \sim 5 { } ^ { \prime \prime } ( \sim 95 pc ) .
The rotation curve flattens beyond this radius , and the isovelocity contours exhibit an S-shaped asymmetry suggestive of a highly inclined bar as has been invoked to produce a similar asymmetry observed on larger scales .
We infer an inclination for the nuclear disk of 62 ^ { \circ } \pm 2 ^ { \circ } , somewhat smaller than the inclination of the large-scale galactic disk of \sim 78 ^ { \circ } .
The continuum emission at 1.3 mm also extends beyond the starburst ring , and is dominated by thermal emission from dust .
If it traces the same dust emitting in the far-infrared , then the bulk of this dust must be heated by star-formation activity rather than the AGN .
We discover a kinematically-decoupled component at the center of the disk with a radius smaller than 1 \hbox { $ . ^ { \prime \prime } $ } 4 ( 27 pc ) , but which spans approximately the same range of velocities as the surrounding disk .
This component has a higher density than its surroundings , and is a promising candidate for the circumnuclear molecular torus invoked by AGN unification models .