Turbulence in Simulated Local Cluster Analogs: One-to-one comparisons between SLOW and XRISM/Hitomi

TL;DR

This study compares simulated galaxy clusters with observations from XRISM, finding that turbulence levels and pressure support in simulations align with observed data, highlighting the importance of selection effects in understanding intra-cluster medium dynamics.

Contribution

It provides a detailed one-to-one comparison between simulated and observed galaxy clusters, improving understanding of ICM turbulence and the impact of selection effects.

Findings

Simulations match observed turbulence levels in galaxy clusters.

Turbulent velocities are a few hundred km/s, consistent with observations.

Turbulent pressure support varies from 1% to 8% within cluster centers.

Abstract

The XRISM Resolve X-ray spectrometer allows to gain detailed insight into gas motions of the intra cluster medium (ICM) of galaxy clusters. Current simulation studies focus mainly on statistical comparisons, making the comparison to the currently still small number of clusters difficult due to unknown selection effects. This study aims to bridge this gap, using simulated counterparts of Coma, Virgo, and Perseus from the SLOW constrained simulations. These clusters show excellent agreement in their properties and dynamical state with observations, thus providing an ideal testbed to understand the processes shaping the properties of the ICM. We find that the simulations match the order of the amount of turbulence for the three considered clusters, Coma being the most active, followed by Perseus, while Virgo is very relaxed. Typical turbulent velocities are a few $\approx100$ km s$^{-1}$, very close to observed values. The resulting turbulent pressure support is $\approx1\%$ for Virgo, $\approx 6\%$ for Perseus, and $\approx 8\%$ for Coma within the central $1-2\%$ of $R_{200}$. Compared to previous simulations and observations, measured velocities and turbulent pressure support are on average lower, in line with XRISM findings, thus indicating the importance of selection effects.