The Weak Carbon Monoxide Emission In An Extremely Metal Poor Galaxy, Sextans A
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.
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.Attached Files
Published - Shi_2015_ApJL_804_L11.pdf
Submitted - 1504.01453v1.pdf
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Additional details
- Eprint ID
- 56847
- Resolver ID
- CaltechAUTHORS:20150421-194124894
- 11373021
- Natural Science Foundation of China (NSFC)
- XDB09000000
- Chinese Academy of Sciences
- 11390373
- Natural Science Foundation of China (NSFC)
- 11420101002
- Natural Science Foundation of China (NSFC)
- COSMICISM
- European Research Council (ERC)
- Created
-
2015-04-22Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)