期刊
ASTROPHYSICAL JOURNAL
卷 752, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/752/2/112
关键词
galaxies: dwarf; galaxies: individual (I Zw 18); galaxies: ISM
资金
- NASA [JPL-1314022]
- NSF [AST-0838178, AST-0955836]
- Cottrell Scholar award from the RCSA
- INSU/CNRS (France)
- MPG (Germany)
- IGN (Spain)
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [0955836] Funding Source: National Science Foundation
The blue compact dwarf galaxy I Zw 18 is one of the most metal-poor systems known in the local universe (12+log(O/H) = 7.17). In this work we study I Zw 18 using data from Spitzer, Herschel Space Telescope, and IRAM Plateau de Bure Interferometer. Our data set includes the most sensitive maps of I Zw 18, to date, in both the far-infrared and the CO J = 1 -> 0 transition. We use dust emission models to derive a dust mass upper limit of only M-dust <= 1.1 x 10(4) M-circle dot (3 sigma limit). This upper limit is driven by the non-detection at 160 mu m, and it is a factor of 4-10 times smaller than previous estimates (depending on the model used). We also estimate an upper limit to the total dust-to-gas mass ratio of M-Dust/M-gas <= 5.0 x 10(-5). If a linear correlation between the dust-to-gas mass ratio and metallicity (measured as O/H) were to hold, we would expect a ratio of 3.9 x 10(-4). We also show that the infrared spectral energy distribution is similar to that of starbursting systems.
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