A large-scale CO survey of the Galactic center

We present high-resolution CO images of the Galactic center region taken with the 2 x 2 focal-plane array receiver mounted on the 45 m telescope of Nobeyama Radio Observatory. We have collected about 44,000 (CO)-C-12-O-16 (J = 1-0) spectra and over 13,000 (CO)-C-13-O-16 (J = 1-0) spectra with a 34 " (1.4 pc) grid spacing. The (CO)-C-12 mapping area is roughly -1 degrees.5 less than or equal to I less than or equal to + 3 degrees.4 and -0 degrees.6 less than or equal to b less than or equal to +0 degrees.6, which covers almost the full extent of the molecular gas concentration in the Galactic center. These CO images demonstrate extremely complex distribution and kinematics of molecular gas in the Galactic center. While its large-scale behavior can be attributed to the well-known coherent features, bright CO emission arises from a number of compact (d less than or equal to 10 pc) clouds with large velocity widths (Delta V greater than or equal to 30 km s(-1)). The small-scale structure of molecular gas is characterized by filaments, arcs, and shells. The boisterous molecular gas kinematics there may be a result of violent release of kinetic energy by a number of supernova explosions and/or Wolf-Rayet stellar winds.