Interstellar dust: What do we learn from the X-rays?
Abstract
The interstellar dust permeates our Galaxy and plays a crucial role in star formation. It can regulate the temperature of the interstellar medium (ISM) and it is the catalyst for the formation of complex molecules. However, the exact chemical composition of dust grains remains still unclear. The X-ray energy band includes a plethora of transitions from atomic and solid species of elements from carbon to nickel. These are the main constituents of interstellar dust 1. In particular the synergy between high-resolution X-ray spectroscopy and new laboratory measurements is a unique probe to investigate the interstellar dust properties along the galactic plane, such as the dust silicate mixture, crystallinity and grain size 2,3. The chemical composition of dust in the dense and diffuse regions of the ISM can be studied through the absorption features of dust and gas, present in the X-ray spectra of bright X-ray binaries 4,5,6. In this work we present our newly obtained laboratory measurements of dust in the O K edge for a total of 18 dust samples, and the calculated extinction cross sections. The dust samples used here are laboratory analogues of silicates and oxides with astronomical interest. It is believed that their composition represents the cosmic silicate mixture7. We further apply the new extinction models to the astronomical data of a bright source close to the galactic plane, and we unveil the dust properties in this line of sight as well as the physical characteristics of the multi-phase ISM.
[1] Mathis 1998 [2] Zeegers S. et al. 2016, A&A, 599, A117 [3] Rogantini et al. 2018, A&A, 609, A22 [4] Costantini E. et al., 2012, A&A, 539, A32 [5] Pinto C. et al. 2010, A&A, 521, A7 [6] Lee J. et al. 2005, A&A, 622, 970 [7] Drain & Lee 1984- Publication:
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American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23513702P