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http://hdl.handle.net/20.500.12386/28954
Title: | On the dust properties of high-redshift molecular clouds and the connection to the 2175 Å extinction bump | Authors: | Heintz, K. E. Zafar, T. De Cia, A. Vergani, S. D. Jakobsson, P. Fynbo, J. P. U. Watson, D. Japelj, J. Møller, P. COVINO, Stefano Kaper, L. Andersen, A. C. |
Issue Date: | 2019 | Journal: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Number: | 486 | Issue: | 2 | First Page: | 2063 | Abstract: | We present a study of the extinction and depletion-derived dust properties of gamma-ray burst (GRB) absorbers at 1 < z < 3 showing the presence of neutral atomic-carbon (C I). By modelling their parametric extinction laws, we discover a broad range of dust models characterizing the GRB C I absorption systems. In addition to the already well-established correlation between the amount of C I and visual extinction, A<SUB>V</SUB>, we also observe a correlation with the total-to-selective reddening, R<SUB>V</SUB>. All three quantities are also found to be connected to the presence and strength of the 2175 Å dust extinction feature. While the amount of C I is found to be correlated with the SED-derived dust properties, we do not find any evidence for a connection with the depletion-derived dust content as measured from [Zn/Fe] and N(Fe)<SUB>dust</SUB>. To reconcile this, we discuss a scenario where the observed extinction is dominated by the composition of dust particles confined in the molecular gas-phase of the interstellar medium (ISM). We argue that since the depletion level trace non-carbonaceous dust in the ISM, the observed extinction in GRB C I absorbers is primarily produced by carbon-rich dust in the molecular cloud and is therefore only observable in the extinction curves and not in the depletion patterns. This also indicates that the 2175 Å dust extinction feature is produced by dust and molecules in the cold and molecular gas-phase. This scenario provides a possible resolution to the discrepancy between the depletion- and SED-derived amounts of dust in high- z absorbers. | URI: | http://hdl.handle.net/20.500.12386/28954 | URL: | https://academic.oup.com/mnras/article-abstract/486/2/2063/5437691?redirectedFrom=fulltext | ISSN: | 0035-8711 | DOI: | 10.1093/mnras/stz1012 | Bibcode ADS: | 2019MNRAS.486.2063H | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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stz1012.pdf | Pdf editoriale | 1.03 MB | Adobe PDF | View/Open |
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