Journal
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume 457, Issue 2, Pages 1842-1850Publisher
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stw114
Keywords
dust, extinction; galaxies: dwarf; galaxies: evolution; galaxies: high-redshift; galaxies: individual: IZw18; galaxies: individual: SBS0335-052
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Funding
- European Research Council under the European Union / ERC [306476]
- INAF-PRIN
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Although dust content is usually assumed to depend uniquely on metallicity, recent observations of two extremely metal-poor dwarf galaxies have suggested that this may not always be true. At a similar oxygen abundance of similar to 3 per cent Z(aS (TM)), the dust-to-gas and dust-to-stellar mass ratios in SBS 0335-052 and I Zw 18 differ by a factor of 40-70 according to including molecular gas or excluding it. Here, we investigate a possible reason for this dramatic difference through models based on a semi-analytical formulation of chemical evolution including dust. Results suggest that the greater dust mass in SBS 0335-052 is due to the more efficient grain growth allowed by the high density in the cold interstellar medium (ISM), observationally inferred to be almost 20 times higher than in I Zw 18. Our models are able to explain the difference in dust masses, suggesting that efficient dust formation and dust content in galaxies, including those with the highest measured redshifts, depend sensitively on the ISM density, rather than only on metallicity.
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