# Astro 2020: Astromineralogy of interstellar dust with X-ray spectroscopy

## TL;DR

This paper discusses how future X-ray observatories can advance our understanding of interstellar dust composition, origin, and properties through high-resolution spectroscopy and the need for laboratory measurements to interpret these observations.

## Contribution

It highlights the importance of high-resolution X-ray spectroscopy and laboratory measurements in addressing fundamental questions about interstellar dust mineralogy and composition.

## Key findings

- Next-generation X-ray observatories will provide detailed dust mineralogy data.
- Laboratory measurements are essential for interpreting high-resolution X-ray spectra.
- Understanding dust composition helps answer key questions about the interstellar medium.

## Abstract

X-ray absorption fine structure (XAFS) in the 0.2-2 keV band is a crucial component in multi-wavelength studies of dust mineralogy, size, and shape -- parameters that are necessary for interpreting astronomical observations and building physical models across all fields, from cosmology to exoplanets. Despite its importance, many fundamental questions about dust remain open. What is the origin of the dust that suffuses the interstellar medium (ISM)? Where is the missing interstellar oxygen? How does iron, predominantly produced by Type Ia supernovae, become incorporated into dust? What is the main form of carbon in the ISM, and how does it differ from carbon in stellar winds? The next generation of X-ray observatories, employing microcalorimeter technology and $R \equiv \lambda/\Delta \lambda \geq 3000$ gratings, will provide pivotal insights for these questions by measuring XAFS in absorption and scattering. However, lab measurements of mineralogical candidates for astrophysical dust, with R > 1000, are needed to fully take advantage of the coming observations.