Chandra measurements of gas homogeneity and turbulence at intermediate radii in the Perseus Cluster

Abstract

We present a Chandra study of surface brightness fluctuations in the diffuse intracluster medium of the Perseus Cluster. Our study utilizes deep, archival imaging of the cluster core as well as a new mosaic of 29 short 5 ks observations extending in 8 different directions out to radii of r500 ∼ 2.2 r2500. Under the assumption that the distribution of densities at a given radius is log-normally distributed, two important quantities can be derived from the width of the log-normal density distribution on a given spatial scale: the density bias, which is equal to the square root of the clumping factor C; and the one-component turbulent velocity, vk, 1D. We forward-model all contributions to the measured surface brightness, including astrophysical and particle background components, and account for the Poisson nature of the measured signal. Measuring the distribution of surface brightness fluctuations in 1 arcmin2 regions, spanning the radial range 0.3 − 2.2 r2500 (7.8 − 57.3 arcmin), we find a small to moderate average density bias of around $3\%$ at radii below 1.6 r2500. We also infer an average turbulent velocity at these radii of V1D < 400 km s−1. Direct confirmation of our results on turbulent velocities inferred from surface brightness fluctuations should be possible using the X-ray calorimeter spectrometers to be flown aboard the XRISM and Athena observatories.

Cosmic-Ray Acceleration and Magnetic Fields in Galaxy Clusters and Beyond: Insights from Radio Observations

“…In the turbulent re-acceleration model, cosmic rays gain energy from the interaction with the turbulent motions in the ICM. As turbulence is best studied with X-ray observations (e.g., [123][124][125][126][127][128] and references there), it is obvious to study the correlation between the X-ray and radio emissions of radio halos (e.g., [101,117,129,130] and references therein). Especially, a study of the point-to-point correlation between the radio emission and X-ray emission allows us to study the acceleration mechanism and the magnetic field distribution in galaxy clusters [131][132][133].…”

A Generative Model for Realistic Galaxy Cluster X-Ray Morphologies

“…Since the advent of high-spatial-resolution X-ray imaging spectroscopy with the Chandra and XMM-Newton observatories, it has been possible to study in detail features such as shocks and cold fronts (Markevitch & Vikhlinin 2007), gas sloshing (e.g., Ascasibar & Markevitch 2006;Roediger et al 2011;ZuHone et al 2011;Johnson et al 2012;Simionescu et al 2012;Paterno-Mahler et al 2013), cavities associated with feedback from active galactic nuclei (McNamara et al 2000;Fabian 2012), and the cool, dense cores found in some clusters (Peterson & Fabian 2006). More recently, such data have been used in investigations of turbulence (Churazov et al 2012;Zhuravleva et al 2015Zhuravleva et al , 2016Zhuravleva et al , 2018Zhuravleva et al , 2019Arévalo et al 2016) and gas clumping in cluster outskirts (Eckert et al 2015;Mirakhor & Walker 2021;de Vries et al 2023), the latter having been spearheaded by lower-resolution but also lower-background Suzaku observations of relatively nearby systems (Simionescu et al 2011;Urban et al 2011Urban et al , 2014Walker et al 2012aWalker et al , 2012b.…”