Characterization of ICM Temperature Distributions of 62 Galaxy Clusters with XMM-Newton

TL;DR

This study analyzes the temperature distributions of 62 galaxy clusters using XMM-Newton data, revealing that none are perfectly isothermal and that disturbed, non-cool-core, and AGN-free clusters tend to have wider temperature distributions, indicating diverse thermal histories.

Contribution

Introduces a Markov Chain Monte Carlo method to model ICM temperature distributions, providing new insights into cluster thermal properties and their correlations with dynamical states.

Findings

No clusters are perfectly isothermal.

Disturbed and non-cool-core clusters have wider temperature distributions.

Temperature distribution width correlates with median temperature, showing diverse thermal histories.

Abstract

We measure the intracluster medium temperature distributions for 62 galaxy clusters in the HIFLUGCS, an X-ray flux-limited sample, with available X-ray data from XMM-Newton. We search for correlations between the width of the temperature distributions and other cluster properties, including median cluster temperature, luminosity, size, presence of a cool core, AGN activity, and dynamical state. We use a Markov Chain Monte Carlo analysis which models the ICM as a collection of X-ray emitting smoothed particles of plasma. Each smoothed particle is given its own set of parameters, including temperature, spatial position, redshift, size, and emission measure. This allows us to measure the width of the temperature distribution, median temperature, and total emission measure of each cluster. We find that none of the clusters have a temperature width, \sigma_kT, consistent with isothermality. Counterintuitively, we also find that the temperature distribution widths of disturbed, non-cool-core, and AGN-free clusters tend to be wider than in other clusters. A linear fit to \sigma_kT - kT_med finds \sigma_kT ~ 0.20kT_med + 1.08, with an estimated intrinsic scatter of ~ 0.55 keV, demonstrating a large range in ICM thermal histories.