The distribution and kinematics of atomic carbon near the galactic center

The central several parsecs of our Galaxy have been mapped in the 492 GHz ³P₁ to ³P₀ fine-structure transition of C I with the Caltech Submillimeter Observatory. The observed region includes the entire southern half of the circumnuclear disk (CND) and part of its northern half. C I is found to be a good tracer of the outer parts of the CND, with an abundance close to that of CO. The high angular resolution (15 sec) of these observations, coupled with the low opacity of the C I line, provide a clear view of the disk's outer regions. The CND kinematics between radii of approximately 2.3 and 7 pc are found to be dominated by rotation, with a rotational velocity, 120 km/s, which is independent of radius. The implied central mass increases roughly linearly with radius, with, in the spherically symmetric case, a slope of 3.3 x 10⁶ solar mass/pc reaching a total of 23 x 10⁶ solar mass at the CND's periphery.