[View Abstracts by Session]

Session: Stars, Planets and the Interstellar Medium

Name: Dr. Ioanna Psaradaki (University of Michigan)
Coauthors: No coauthors were included.
Type: Oral
Title: Mineralogy of interstellar dust in the X-ray regime
Abstract:

Interstellar dust is an important ingredient of the interstellar medium (ISM) of galaxies. High-resolution X-ray spectroscopy is a powerful tool for studying interstellar dust mineralogy. X-ray absorption fine structures (XAFS) are oscillatory modulations observed near the X-ray photoelectric absorption edges, and their shape is the ultimate footprint of the dust chemical composition, size and lattice structure. In this presentation I will demonstrate the newest laboratory measurements of XAFS from astrophysical dust templates in the O K and Fe L photoabsorption edges (Psaradaki et al. 2020,2021), and their application to high-resolution X-ray spectra of a sample of bright Galactic X-ray sources. I will present recent results (Psaradaki et al. 2022) on dust mineralogy in the diffuse regions in our Galaxy using XMM-Newton/RGS and Chandra/HETGS observations. This study gave the most comprehensive view of the silicate mineralogy in the diffuse regions of ISM, through the X-ray energy band. We found that the Mg-rich amorphous pyroxene dust composition (Mg0.75Fe0.25SiO3), and metallic iron represents the bulk of the dust chemistry in the diffuse ISM. Finally, I will discuss the prospects of studying the dust grain chemistry in denser regions of the ISM through the new X-ray Imaging and Spectroscopy mission, XRISM, which will be launched in the summer of 2023.