CHEX-MATE: Robust reconstruction of temperature profiles in galaxy clusters with XMM-Newton^⋆

¹ INAF, IASF-Milano, Via A. Corti 12, 20133 Milano, Italy
e-mail: mariachiara.rossetti@inaf.it
² Department of Astronomy, University of Geneva, Ch. d’Ecogia 16, 1290 Versoix, Switzerland
³ INAF, Osservatorio di Trieste, Via Tiepolo 11, 34131 Trieste, Italy
⁴ IFPU, Institute for Fundamental Physics of the Universe, Via Beirut 2, 34014 Trieste, Italy
⁵ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
⁶ INAF, Osservatorio di Astrofisica e Scienza dello Spazio, Via Piero Gobetti 93/3, 40129 Bologna, Italy
⁷ INFN, Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
⁸ DiSAT, Università degli Studi dell’Insubria, Via Valleggio 11, 22100 Como, Italy
⁹ Astronomy Unit, Department of Physics, University of Trieste, Via Tiepolo 11, 34131 Trieste, Italy
¹⁰ Università degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica, 1, 00133 Roma, Italy
¹¹ INFN, Sezione di Roma 2, Università degli studi di Roma Tor Vergata, Via della Ricerca Scientifica, 1, Roma, Italy
¹² INAF, Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate, Italy
¹³ Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185 Roma, Italy
¹⁴ Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
¹⁵ Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
¹⁶ Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University of Manchester, Alan Turing Building, Manchester M13 9PL, UK
¹⁷ HH Wills Physics Laboratory, University of Bristol, Tyndall Ave, Bristol BS8 1TL, UK
¹⁸ IRAP, Université de Toulouse, CNRS, CNES, UPS, 9 Av. du Colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
¹⁹ Dipartimento di Fisica, Università degli Studi di Milano, Via G. Celoria 16, 20133 Milano, Italy
²⁰ California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA

Received: 5 December 2023
Accepted: 26 February 2024

Abstract

The “Cluster HEritage project with XMM-Newton: Mass Assembly and Thermodynamics at the End point of structure formation” (CHEX-MATE) is a multi-year heritage program to obtain homogeneous XMM-Newton observations of a representative sample of 118 galaxy clusters. The observations are tuned to reconstruct the distribution of the main thermodynamic quantities of the intra-cluster medium up to R₅₀₀ and to obtain individual mass measurements, via the hydrostatic-equilibrium equation, with a precision of 15−20%. Temperature profiles are a necessary ingredient for the scientific goals of the project and it is thus crucial to derive the best possible temperature measurements from our data. This is why we have built a new pipeline for spectral extraction and analysis of XMM-Newton data, based on a new physically motivated background model and on a Bayesian approach with Markov chain Monte Carlo methods, which we present in this paper for the first time. We applied this new method to a subset of 30 galaxy clusters representative of the CHEX-MATE sample and show that we can obtain reliable temperature measurements up to regions where the source intensity is as low as 20% of the background, keeping systematic errors below 10%. We compare the median profile of our sample and the best-fit slope at large radii with literature results and we find a good agreement with other measurements based on XMM-Newton data. Conversely, when we exclude the most contaminated regions, where the source intensity is below 20% of the background, we find significantly flatter profiles, in agreement with predictions from numerical simulations and independent measurements with a combination of Sunyaev–Zeldovich and X-ray imaging data.