CHEX-MATE: Relationship between X-ray and millimetre inferences of galaxy cluster temperature profiles

TL;DR

This study compares X-ray and millimetre inferences of galaxy cluster temperature profiles using joint XMM-Newton and Planck data, revealing a near-unity temperature ratio with morphology-dependent scatter and minimal redshift or mass dependence.

Contribution

It provides the first comprehensive analysis of the temperature ratio between X-ray and SZ measurements across a large cluster sample, including relativistic and absorption corrections.

Findings

Mean temperature ratio $ eq$ 1.0 is negligible, indicating consistency between methods.

Cluster morphology significantly influences temperature measurement scatter.

Relativistic corrections and molecular hydrogen absorption affect the temperature ratio estimates.

Abstract

Thermodynamic profiles from X-ray and millimetre observations of galaxy clusters are often compared under the simplifying assumptions of smooth, spherically symmetric intracluster medium. These approximations lead to expected discrepancies in the inferred profiles, which can provide insights about the cluster structure or cosmology. Motivated by this, we present a joint XMM-\textit{Newton} and \textit{Planck} analysis of 116 CHEX-MATE clusters to measure $\eta_T = T_X/T_{SZ,X}$, the ratio between spectroscopic X-ray temperatures and a temperature proxy derived from Sunyaev-Zel'dovich (SZ) pressures and X-ray densities. We considered relativistic corrections to the thermal SZ signal and implemented X-ray absorption by Galactic molecular hydrogen. The $\eta_T$ distribution has a mean of $1.01 \pm 0.03$, with average changes of $8.1\%$ and $2.7\%$ when relativistic corrections and molecular hydrogen absorption are not included, respectively. The $\eta_T$ distribution is positively skewed, with the scatter mostly affected by cluster morphology: relaxed clusters are closer to unity and less scattered than mixed and disturbed systems. We find little or no correlation with redshift, mass, or temperature.