A LARGE-SCALE CO SURVEY OF THE GALACTIC CENTER

Tomoharu Oka(1), Tetsuo Hasegawa(2), Fumio Sato(3), Masato Tsuboi(4), and Atsushi Miyazaki(4)

(1) size The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
(2) size Institute of Astronomy, Faculty of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan.
(3) size Department of Astronomy and Earth Sciences, Tokyo Gakugei University, 4-1-1 Nukui-kita, Koganei, Tokyo 184-8501, Japan.
(4) size Institute of Astrophysics and Planetary Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan.

Paper: ApJS, vol.118, 455-515

Abstract:

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 mark[1] . We have collected about 44000 ¹²C¹⁶O (J=1-0) spectra and over 13000 ¹³C¹⁶O (J=1-0) spectra with a 34'' (1.4 pc) grid spacing. ¹²CO mapping area is roughly -1.5\arcdeg <= l <= +3.4\arcdeg and -0.6\arcdeg <= b <= +0.6\arcdeg, 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 ( DELTA V >= 30 km/sec ). 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.

Preprints available from the authors at oka@postman.riken.go.jp , or the raw TeX (no figures) if you click here.

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