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The Weak Carbon Monoxide Emission In An Extremely Metal Poor Galaxy, Sextans A

Shi, Yong and Wang, Junzhi and Zhang, Zhi-Yu and Gao, Yu and Armus, Lee and Helou, George and Gu, Qiusheng and Stierwalt, Sabrina (2015) The Weak Carbon Monoxide Emission In An Extremely Metal Poor Galaxy, Sextans A. Astrophysical Journal Letters, 804 (1). Art. No. L11. ISSN 2041-8205. http://resolver.caltech.edu/CaltechAUTHORS:20150421-194124894

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Abstract

Carbon monoxide (CO) is one of the primary coolants of gas and an easily accessible tracer of molecular gas in spiral galaxies, but it is unclear if CO plays a similar role in metal-poor dwarfs. We carried out a deep observation with IRAM 30 m to search for CO emission by targeting the brightest far-IR peak in a nearby extremely metal-poor galaxy, Sextans A, with 7% solar metallicity. A marginal signal of CO J = 1 − 0 emission is seen, which is already faint enough to place a strong constraint on the conversion factor (ɑ_(CO)) from the CO luminosity to the molecular gas mass that is derived from the spatially resolved dust-mass map. The ɑ_(CO) is at least seven hundred times the Milky Way value. This indicates that CO emission is exceedingly weak in Sextans A, challenging its role as a coolant in extremely metal-poor galaxies.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1088/2041-8205/804/1/L11DOIArticle
http://arxiv.org/abs/1504.01453arXivDiscussion Paper
ORCID:
AuthorORCID
Shi, Yong0000-0002-8614-6275
Stierwalt, Sabrina0000-0002-2596-8531
Additional Information:© 2015 American Astronomical Society. Received 2015 January 21; accepted 2015 April 3; published 2015 April 24. Based on observations carried out with the IRAM 30 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). We thank the anonymous referee for constructive comments that significantly improved the paper. Y.S. acknowledges support for this work from Natural Science Foundation of China under grant 11373021 and by the Strategic Priority Research Program “The Emergence of Cosmological Structures” of the Chinese Academy of Sciences, grant No. XDB09000000. Y.G. is supported under grants 11390373, 11420101002, and XDB09000000. Z.Y.Z. acknowledges support from the European Research Council (ERC) in the form of an Advanced Grant, COSMICISM.
Group:Infrared Processing and Analysis Center (IPAC)
Funders:
Funding AgencyGrant Number
Natural Science Foundation of China (NSFC)11373021
Chinese Academy of SciencesXDB09000000
Natural Science Foundation of China (NSFC)11390373
Natural Science Foundation of China (NSFC)11420101002
European Research Council (ERC)COSMICISM
Subject Keywords:galaxies: dwarf; galaxies: ISM; submillimeter: ISM
Record Number:CaltechAUTHORS:20150421-194124894
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20150421-194124894
Official Citation:The Weak Carbon Monoxide Emission in an Extremely Metal-poor Galaxy, Sextans A Yong Shi et al. 2015 ApJ 804 L11
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:56847
Collection:CaltechAUTHORS
Deposited By: Joy Painter
Deposited On:22 Apr 2015 19:22
Last Modified:14 Aug 2018 17:00

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