Journal article
OBSERVATIONAL CONSTRAINTS ON THE MOLECULAR GAS CONTENT IN NEARBY STARBURST DWARF GALAXIES
The Astrophysical journal, Vol.751(2), pp.1-8
06/01/2012
DOI: 10.1088/0004-637X/751/2/127
Abstract
Using star formation histories derived from optically resolved stellar populations in 19 nearby starburst dwarf galaxies observed with the Hubble Space Telescope, we measure the stellar mass surface densities of stars newly formed in the bursts. By assuming a star formation efficiency (SFE), we then calculate the inferred gas surface densities present at the onset of the starbursts. Assuming an SFE of 1%, as is often assumed in normal star-forming galaxies, and assuming that the gas was purely atomic, translates to very high Hi surface densities (similar to 10(2)-10(3) M-circle dot pc(-2)), which are much higher than have been observed in dwarf galaxies. This implies either higher values of SFE in these dwarf starburst galaxies or the presence of significant amounts of H-2 in dwarfs (or both). Raising the assumed SFEs to 10% or greater (in line with observations of more massive starbursts associated with merging galaxies), still results in Hi surface densities higher than observed in 10 galaxies. Thus, these observations appear to require that a significant fraction of the gas in these dwarf starbursts galaxies was in the molecular form at the onset of the bursts. Our results imply molecular gas column densities in the range 10(19)-10(21) cm(-2) for the sample. In the galaxies where CO observations have been made, these densities correspond to values of the CO-H-2 conversion factor (X-CO) in the range >(3-80) x 10(20) cm(-2) (K km s(-1))(-1), or up to 40x greater than Galactic X-CO values.
Details
- Title: Subtitle
- OBSERVATIONAL CONSTRAINTS ON THE MOLECULAR GAS CONTENT IN NEARBY STARBURST DWARF GALAXIES
- Creators
- Kristen B. W. McQuinn - University of MinnesotaEvan D. Skillman - University of MinnesotaJulianne J. Dalcanton - University of WashingtonAndrew E. Dolphin - RTXJohn M. Cannon - Macalester CollegeJon Holtzman - New Mexico State UniversityDaniel R. Weisz - University of WashingtonBenjamin F. Williams - University of Washington
- Resource Type
- Journal article
- Publication Details
- The Astrophysical journal, Vol.751(2), pp.1-8
- Publisher
- IOP Publishing Ltd
- DOI
- 10.1088/0004-637X/751/2/127
- ISSN
- 0004-637X
- eISSN
- 1538-4357
- Number of pages
- 8
- Grant note
- NAS 5-26555 / NASA; National Aeronautics & Space Administration (NASA) NNX10AD57G / NASA through ROSES
- Language
- English
- Date published
- 06/01/2012
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984627204902771
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