Search for the CO-dark mass in the central molecular zone by using the ASTE 10-m telescope

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Abstract

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.

Original languageEnglish
Pages (from-to)107-110
Number of pages4
JournalProceedings of the International Astronomical Union
Volume11
DOIs
Publication statusPublished - 2016

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Keywords

  • Molecular clouds

ASJC Scopus subject areas

  • Astronomy and Astrophysics

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