ASTE CO <i>J</i> = 3-2 SURVEY OF THE GALACTIC CENTER

Abstract

We present high-resolution CO J = 3–2 maps of the Galactic center region, taken with the ASTE 10 m telescope. We have collected approximately 30,000 spectra with a 34'' grid spacing. The mapping area is roughly −18 < l < +35 and −08 < b < +09, which includes the central molecular zone and Bania's Clump 2, covering almost the full extent of the molecular gas concentration in the Galactic center. These CO J = 3–2 images show a behavior similar to the CO J = 1–0 images with the same resolution. Molecular gas in the Galactic center shows a higher J = 3–2/J = 1–0 intensity ratio (∼0.7) than the gas in the spiral arms in the Galactic disk (∼0.4). The CO J = 3–2/CO J = 1–0 luminosity ratio is 0.71. We see several regions with very high J = 3–2/J = 1–0 intensity ratios exceeding 1.5, including the Sgr A, l = +13, l = −04, and l = −12 regions. A number of small spots of high ratio gas are also found. Many of them have large velocity widths, indicating that they are spots of hot molecular gas shocked by unidentified supernovae and/or winds from massive stars.