The 200-pc Molecular Cylinder in the Galactic Centre

Abstract

Analyzing the 3D structure of the molecular gas distribution in the central 200 pc region of the Galaxy, we show that the expanding molecular ring (EMR, also known as the parallelogram) and the central molecular zone (CMZ) exhibit quite different distributions and kinematics. The EMR composes a bipolar vertical cylinder with the total length as long as $\sim 170$ pc and shows large non-circular velocities. On the contrary, the CMZ is distributed in a nearly rigid-body rotating ring and arms tightly concentrated near the galactic plane with full thickness less than $\sim 30$ pc. Furthermore, the mass and density ratios of the EMR to CMZ are as small as $\sim 0.13$ and $0.04$, respectively. We discuss the origins of the EMR and CMZ based on the bar and explosion models. We suggest that the EMR's large vertical extent can be explained by a cylindrical shock wave model driven by an explosive activity in the Galactic Centre.

MNRAS to appear, 9 pages, 13 figures, 1 table

References in corpus (2)

• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• Gas flow models in the Milky Way embedded bars

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• Giant HI Hole inside the 3-kpc Ring and the North Polar Spur - The Galactic Crater -
• Star Formation in Extreme Environments: A 200 pc High Velocity Gas Stream in the Galactic Centre
• Feedback between Sgr A and B : AGN-Starburst Connection in the Galactic Centre
• One-kpc Expanding Cylinder of HI-Gas around the Galactic Center