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|Title:||On the dust properties of high-redshift molecular clouds and the connection to the 2175 Å extinction bump||Authors:||Heintz, K. E.
De Cia, A.
Vergani, S. D.
Fynbo, J. P. U.
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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