Molecular Gas in the Inner 100 Parsecs of M51

We report imaging of CO (2-1) emission in the nucleus of M51 at 1^'' (47 pc) resolution. Molecular gas is found closely associated with the nuclear radio jet and the X-shaped dust absorption feature seen in the Hubble Space Telescope images. The CO emission lies along the side of the nuclear radio continuum ``jet.'' The strongest molecular emission is not symmetric in either position or velocity with respect to the nucleus--the dominant feature is at redshifted velocities and peaks 1^'' to the west of the radio/optical nucleus. The CO (2-1) emission has an integrated flux implying a molecular gas mass of 10⁷ M_solar for a standard Galactic giant molecular cloud CO-to-H₂ conversion ratio, which is consistent with the total virial mass of the individual complexes. The redshifted CO emission is elongated with a deconvolved semimajor axis of 65 pc (1.38"). Assuming the molecular gas moves in circular orbit about the nucleus (defined by the point radio source), we find a dynamical mass of 2×10⁸ M_solar at R>=47 pc with no correction for inclination. The molecular gas has sufficient density (>=10⁵ cm^-3) to collimate the radio jet and ionized outflow from the active galactic nucleus (AGN), and this gas may in fact be the reservoir of matter that supplies the AGN.