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Search for the CO-dark Mass in the Central Molecular Zone by using the ASTE 10-m Telescope

Published online by Cambridge University Press:  09 February 2017

Kunihiko Tanaka
Kunihiko Tanaka*
Affiliation:
Institute of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama, Japan email: ktanaka@phys.keio.ac.jp
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Abstract

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Atomic carbon (C0) is one of the most abundant carbon-bearing species in the interstellar molecular gas, and its submillimeter lines are good tracers of low-density molecular clouds which are often dark in CO rotational lines. We present a new map of the central 150 pc region of the Milky Way in the 500 GHz [CI] line, which has been recently obtained with the ASTE 10-m telescope. The [CI] emission is brightest toward the central 5-pc region, where massive GMCs are absent. This [CI]-bright region is approximately centered toward Sgr A*, covering the entire circum-nuclear ring (CND) and the western part of the 50-km/s cloud. The C0/CO abundance ratio is 0.5–2 there, and the highest ratio is observed toward the CND but just outside of the 2-pc ring of dense gas. This discovery may suggest that the CO-dark component occupies a significant fraction of the molecular gas in the circumnuclear region.

Keywords

Molecular clouds
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Symposium S322: The Multi-Messenger Astrophysics of the Galactic Centre , July 2016 , pp. 107 - 110
Copyright
Copyright © International Astronomical Union 2017 

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