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 ∼3 per cent Z⊙, 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.

The dust content of the most metal-poor star-forming galaxies / Schneider, Raffaella; Hunt, Leslie; Valiante, Rosa. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 457:2(2016), pp. 1842-1850. [10.1093/mnras/stw114]

The dust content of the most metal-poor star-forming galaxies

SCHNEIDER, Raffaella;
2016

Abstract

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 ∼3 per cent Z⊙, 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.
2016
Dust, extinction; galaxies: dwarf; galaxies: evolution; high-redshift; galaxies individual: IZw18; SBS0335-052; Astronomy and Astrophysics; Space and Planetary Science
01 Pubblicazione su rivista::01a Articolo in rivista
The dust content of the most metal-poor star-forming galaxies / Schneider, Raffaella; Hunt, Leslie; Valiante, Rosa. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 457:2(2016), pp. 1842-1850. [10.1093/mnras/stw114]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/939304
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