A large-scale CO survey of the galactic center

We present high-resolution CO images of the Galactic center region taken with the 2 × 2 focal-plane array receiver mounted on the 45 m telescope of Nobeyama Radio Observatory. We have collected about 44,000 ¹²C¹⁶O (J = 1-0) spectra and over 13,000 ¹³C¹⁶O (J = 1-0) spectra with a 34″ (1.4 pc) grid spacing. The ¹²CO mapping area is roughly - 1°.5 ≤ l ≤ + 3°.4 and -0°.6 ≤ b ≤ +0°.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 ≤ 10 pc) clouds with large velocity widths (ΔV ≥ 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.