CHEX-MATE: Are we getting cluster thermodynamics right?

¹ Department of Astronomy, University of Geneva, Ch. d’Ecogia 16, CH-1290 Versoix, Switzerland
² INAF – Osservatorio Astronomico di Trieste, Via Tiepolo 11, I-34131 Trieste, Italy
³ Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
⁴ Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
⁵ Excellence Cluster ORIGINS, Boltzmannstr. 2, D-85748 Garching bei München, Germany
⁶ Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians-Universität München, Scheinerstr.1, 81679 München, Germany
⁷ Max-Planck-Institut für Astrophysik, Karl-Schwarzschildstr. 1, 85741 Garching bei München, Germany
⁸ IFPU, Institute for Fundamental Physics of the Universe, Via Beirut 2, I-34014 Trieste, Italy
⁹ INAF, Osservatorio di Astrofisica e Scienza dello Spazio, Via Piero Gobetti 93/3, I-40129 Bologna, Italy
¹⁰ INFN, Sezione di Bologna, Viale Berti Pichat 6/2, I-40127 Bologna, Italy
¹¹ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM de Paris-Saclay, 91191 Gif-sur-Yvette, France
¹² IRAP, CNRS, Université de Toulouse, CNES, Toulouse, France
¹³ INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano, Via A. Corti 12, 20133 Milano, Italy
¹⁴ Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 5, I-000185 Rome, Italy
¹⁵ Department of Physics, Informatics and Mathematics, University of Modena and Reggio Emilia, 41125 Modena, Italy
¹⁶ Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
¹⁷ Dipartimento di Fisica, Università di Roma ‘Tor Vergata’, Via della Ricerca Scientifica 1, I-00133 Roma, Italy
¹⁸ INFN, Sezione di Roma ‘Tor Vergata’, Via della Ricerca Scientifica, 1, 00133 Roma, Italy
¹⁹ California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
²⁰ Departamento de Física Teórica M-8, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
²¹ Centro de Investigación Avanzada en Física Fundamental (CIAFF), Universidad Autónoma de Madrid, E-28049 Madrid, Spain

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 12 December 2025
Accepted: 19 June 2026

Abstract

Context. Galaxy clusters offer powerful insights into the large-scale structure of the Universe and the physics of baryons in hot states. Their scientific exploitation, however, hinges on our ability to accurately measure key thermodynamic properties.

Aims. In this work we assess the reliability of current analysis techniques in reconstructing these properties, with a particular focus on samples similar to those observed in the Cluster Heritage project with XMM-Newton (CHEX-MATE).

Methods. We developed a suite of dedicated end-to-end simulations of CHEX-MATE-like clusters selected from large-scale hydrodynamical simulations and processed through a newly developed realistic XMM-Newton simulator. We applied a full X-ray data analysis pipeline that includes imaging, spectral fitting, and profile reconstruction to the mock datasets.

Results. The gas density profiles can be robustly recovered across a wide radial range when using azimuthal mean surface brightness profiles. Our reconstruction techniques are able to reproduce the intrinsic density profile with the correct scatter, with deviations of at most 10% between 0.1 and 1 × R_500c. The gas mass is reconstructed with better than 1% accuracy. The accurate measurement of temperature profiles is more challenging and possibly subject to biases, particularly in the presence of azimuthal variations and multi-temperature gas along the line of sight, which dominate over projection effects.

Conclusions. Our results highlight the need for caution when interpreting cluster temperature measurements and underscore the value of tailored mock observations for understanding observational systematics. These findings also suggest that biases in X-ray temperature measurements alter the interpretation of the thermodynamical state of the intra-cluster medium, an outlook particularly relevant in light of recent low-velocity measurements from the XRISM mission.