Nuclear Rotation Curves of Galaxies in the CO Line Emission

We have obtained high-resolution position-velocity (PV) diagrams along the major axes of the central regions of nearby galaxies in the CO-line emission using the Nobeyama 45-m telescope and the Millimeter Array. Nuclear rotation curves for 14 galaxies have been derived based on the PV diagrams using the envelope-tracing method. The nuclear rotation curves for most of the galaxies show a steep rise within a few hundred pc, which indicates a high-density concentration of mass. Keywords: Galaxies: general - Galaxies: structure - ISM: molecular line