High-resolution X-ray spectroscopy: the coming-of-age

TL;DR

High-resolution X-ray spectroscopy has advanced significantly with new missions, enabling detailed studies of a wider range of cosmic sources beyond the brightest objects, and promising further scientific breakthroughs.

Contribution

This paper reviews recent progress in high-resolution X-ray spectroscopy and discusses future prospects with upcoming missions like Arcus and Athena.

Findings

Hitomi provided the first high-quality spectrum of an extended source.

Current and upcoming missions will expand spectral studies to many more sources.

Spectroscopy will enable detailed investigations of distant and variable cosmic phenomena.

Abstract

Since the launch of Chandra and XMM-Newton, high-resolution X-ray spectra of cosmic sources of all kinds have become available. These spectra have resulted in major scientific breakthroughs. However, due to the techniques used, in general high-quality spectra can only be obtained for the brightest few sources of each class. Moreover, except for the most compact extended sources, like cool core clusters, grating spectra are limited to point sources. Hitomi made another major step forward, in yielding for the first time a high-quality spectrum of an extended source, and improved spectral sensitivity in the Fe-K band. For point sources with the proposed Arcus mission, and for all sources with the launch of Athena, X-ray spectroscopy will become mature. It allows us to extend the investigations from the few handful of brightest sources of each category to a large number of sources far away in space and time, or to get high time-resolution, high-spectral resolution spectra of bright time variable sources.