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Paper: The ASTE Galactic Center Survey in the 350 and 500 GHz Bands
Volume: 476, New Trends in Radio Astronomy in the ALMA Era
Page: 77
Authors: Tanaka, K.; Oka, T.; Matsumura, S.; Kamegai, K.; Nagai, M.
Abstract: The Galactic central molecular zone (CMZ) provides us with a unique opportunity to study the properties of the molecular clouds in the extreme environment of the central region of a galaxy. We present the HCN J=4–3 and [CI] 3P1-3P0 data taken with the Atacama Submillimeter Telescope Experiment (ASTE). The HCN J=4–3 line is a tracer of very high density (∼ 106 cm-3) region. Bright HCN emission is detected toward several compact clumps with very large velocity width (80-100 km s-1) without apparent energy sources. We have also found two large molecular shells near the Sgr C complex in the HCN map. The [CI] forbidden line from atomic carbon (Cn) traces molecular gas in different conditions than that traced by CO lines. We have discovered a large molecular cloud structure unseen in CO maps, at a distance of 5 pc from the Galactic nucleus. This [CI] cloud may be a site of accumulation of infalling material from outer region, or a cloud exposed to high cosmic-ray or X-ray flux.
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