Radial temperature profiles for a large sample of galaxy clusters observed with XMM-Newton

TL;DR

This study measures radial temperature profiles of about 50 galaxy clusters using XMM-Newton data, employing advanced background modeling and systematic error assessment to improve accuracy and compare with simulations.

Contribution

It introduces a novel approach using background modeling and detailed systematic analysis to reliably measure cluster temperature profiles at large radii.

Findings

Temperature declines beyond 0.2 R_{180}

Systematic uncertainties are quantified and controlled

Profiles are consistent with hydrodynamic simulations

Abstract

Aims. We measure, as far out as possible, radial temperature profiles for a sample of ~50 hot, intermediate redshift galaxy clusters, selected from the XMM-Newton archive, keeping systematic errors under control. Methods. Our work is characterized by two major improvements. Firstly, we use the background modeling, rather than the background subtraction, and the Cash statistic rather than the chi square; this method requires a careful characterization of all background components. Secondly, we assess in details systematic effects. We perform two groups of test: prior to the analysis, we make use of extensive simulations to quantify the impact of different spectral components on simulated spectra; after the analysis, we investigate how the measured temperature profile changes, when choosing different key parameters. Results. The mean temperature profile declines beyond 0.2 R_{180}; for the first time we provide an assessment of the source and the magnitude of systematic uncertainties. When comparing our profile with that obtained from hydrodynamic simulations, we find the slopes beyond ~0.2 R_{180} to be similar. Our mean profile is similar but somewhat flatter with respect to that obtained by previous observational works, possibly as a consequence of a different level of characterization of systematic effects. Conclusions. This work allows us not only to constrain with confidence cluster temperature profiles in outer regions, but also, from a more general point of view, to explore the limits of the current X-ray experiments (in particular XMM-Newton) with respect to the analysis of low surface brightness emission.