Abstract
Context. The composition and properties of interstellar silicate dust are not well understood. In X-rays, interstellar dust can be studied in detail by making use of the fine structure features in the Si K-edge. The features in the Si K-edge offer a range of possibilities to study silicon-bearing dust, such as investigating the crystallinity, abundance, and the chemical composition along a given line of sight. Aims. We present newly acquired laboratory measurements of the silicon K-edge of several silicate-compounds that complement our measurements from our earlier pilot study. The resulting dust extinction profiles serve as templates for the interstellar extinction that we observe. The extinction profiles were used to model the interstellar dust in the dense environments of the Galaxy. Methods. The laboratory measurements, taken at the Soleil synchrotron facility in Paris, were adapted for astrophysical data analysis and implemented in the SPEX spectral fitting program. The models were used to fit the spectra of nine low-mass X-ray binaries located in the Galactic center neighborhood in order to determine the dust properties along those lines of sight. Results. Most lines of sight can be fit well by amorphous olivine. We also established upper limits on the amount of crystalline material that the modeling allows. We obtained values of the total silicon abundance, silicon dust abundance, and depletion along each of the sightlines. We find a possible gradient of 0.06 ± 0.02 dex/kpc for the total silicon abundance versus the Galactocentric distance. We do not find a relation between the depletion and the extinction along the line of sight.
| Original language | English |
|---|---|
| Article number | A16 |
| Number of pages | 18 |
| Journal | Astronomy and Astrophysics |
| Volume | 627 |
| DOIs | |
| Publication status | Published - 1 Jul 2019 |
Bibliographical note
Funding Information:Acknowledgements. We would like to thank the anonymous referee for providing us with helpful comments. Dust studies at Leiden Observatory are supported through the Spinoza Premie of the Dutch science agency, NWO. E.C. and D.R. acknowledge support from NWO-Vidi grant 639.042.525. H.M. and P.M. are grateful for the support of the Deutsche Forschungsgemeinschaft under Mu 1164/8-2 and Mu 1164/9-1. We acknowledge SOLEIL for provision of synchrotron radiation facilities, and we would like to thank Delphine Vantelon for assistance in using beamline LUCIA. This research made use of the Chan-dra Transmission Grating Catalog and archive (http://tgcat.mit.edu). We also made use of the FLUO self-absorption correction code provided by Daniel Haskel.
Publisher Copyright:
© ESO 2019.
Funding
Acknowledgements. We would like to thank the anonymous referee for providing us with helpful comments. Dust studies at Leiden Observatory are supported through the Spinoza Premie of the Dutch science agency, NWO. E.C. and D.R. acknowledge support from NWO-Vidi grant 639.042.525. H.M. and P.M. are grateful for the support of the Deutsche Forschungsgemeinschaft under Mu 1164/8-2 and Mu 1164/9-1. We acknowledge SOLEIL for provision of synchrotron radiation facilities, and we would like to thank Delphine Vantelon for assistance in using beamline LUCIA. This research made use of the Chan-dra Transmission Grating Catalog and archive (http://tgcat.mit.edu). We also made use of the FLUO self-absorption correction code provided by Daniel Haskel.
Keywords
- Dust, extinction
- ISM: abundances
- X-rays: binaries