Gas Turbulent Motions in Galaxy Clusters

TL;DR

This paper explores methods to measure turbulence in galaxy clusters' intracluster medium using X-ray lines, employing simulations and radiative transfer to understand how velocity fields influence observable properties.

Contribution

It introduces a calibrated relation between observable X-ray line features and the 3D velocity power spectrum of turbulence in galaxy clusters.

Findings

Radial motions significantly impact resonant scattering effects.

Tangential motions have a weaker influence on resonant scattering.

Simulations effectively connect velocity field properties to X-ray observables.

Abstract

We discuss various possibilities to constrain ICM turbulence in galaxy clusters using bright X-ray lines. Numerical simulations are used to find the most appropriate description of the 3D velocity field power spectrum (PDS) and to calibrate the relation of observables to this PDS. The impact of the velocity field on the surface brightness distribution and on the spectral shape of strong X-ray lines, modified by the resonant scattering (RS), is evaluated via radiative transfer calculations. We investigate the sensitivity of RS not only to amplitudes of motions, but also to anisotropy and spatial scales. We in particular show that the amplitude of radial motions is most important for RS, while tangential motions only weakly affect the scattering.