Resonant scattering in the Perseus Cluster: spectral model for constraining gas motions with Astro-H

TL;DR

This paper develops self-consistent spectral models to analyze resonant scattering effects in galaxy cluster spectra, aiming to improve measurements of gas motions and metal abundances with future Astro-H data.

Contribution

It introduces comprehensive spectral models that incorporate resonant scattering, gas properties, and motions, enabling more accurate analysis of cluster spectra.

Findings

Current CCD data cannot robustly detect resonant scattering effects.

Future Astro-H observations will significantly improve constraints on gas turbulence.

Models are publicly available for direct comparison with observed spectra.

Abstract

X-ray spectra from cores of galaxy clusters can be strongly distorted by resonant scattering of line photons, affecting metal abundance and gas velocity measurements. We introduce simulated spectral models that take into account the resonant scattering effect, radial variations of thermodynamic properties of the hot gas, projection effects and small-scale isotropic gas motions. The key feature of the models is that all these effects are treated self-consistently for the whole spectrum, rather than for individual lines. The model spectra are publicly available and can be used for direct comparison with observed projected spectra. Comparison with the existing XMM-Newton and Chandra data of the Perseus Cluster shows that even though there is no strong evidence for the resonant scattering in Perseus, the low energy resolution of the X-ray CCDs is not sufficient to robustly distinguish spectral distortions due to the resonant scattering, different metal abundance profiles and different levels of gas turbulence. Future Astro-H data will resolve most of the problems we are facing with CCDs. With the help of our models, the resonant scattering analysis can be done self-consistently using the whole spectral information, constraining the level of gas turbulence already with a 100 ks observation with Astro-H.