Chemical composition and enrichment of the Centaurus cluster core seen by XRISM/Resolve

¹ IRAP, CNRS, Université de Toulouse, CNES, UT3-UPS Toulouse, France
² Department of Astronomy, University of Maryland 4296 Stadium Dr. College Park MD 20742-2421, USA
³ NASA/Goddard Space Flight Center Greenbelt MD 20771, USA
⁴ Center for Research and Exploration in Space Science and Technology, NASA/GSFC (CRESST II) Greenbelt MD 20771, USA
⁵ Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai Chuo-ku Sagamihara Kanagawa 252-5210, Japan
⁶ SRON Netherlands Institute for Space Research Niels Bohrweg 4 2333 CA Leiden, The Netherlands
⁷ Department of Physics, Saitama University, 255 Shimo-Okubo, Sakura Saitama Saitama 338-8570, Japan
⁸ Waterloo Centre for Astrophysics, Department of Physics and Astronomy 200 University Avenue West Waterloo N2L 3G1, Canada
⁹ Department of Theoretical Physics and Astrophysics, Faculty of Science, Masaryk University Kotlářská 2 Brno 611 37, Czech Republic
¹⁰ Department of Physics, Tokyo Metropolitan University, 1-1 Minami-Osawa Hachioji Tokyo 192-0397, Japan
¹¹ Department of Astrophysics and Atmospheric Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku Kyoto 603-8555, Japan
¹² Faculty of Physics, Tokyo University of Science, 1-3 Kagurazaka Shinjuku-ku Tokyo 162-8601, Japan
¹³ Department of Physics, Hiroshima University, 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima 739-8526, Japan
¹⁴ Faculty of Engineering, University of Miyazaki, 1-1 Gakuen-kibanadai-nishi Miyazaki Miyazaki 889-2192, Japan
¹⁵ Department of Physics, Nagoya University, Furo-cho, Chikusa-ku. Nagoya Aichi 464-8602, Japan

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Received: 26 September 2025
Accepted: 9 December 2025

Abstract

Context. Hot, X-ray emitting atmospheres pervading galaxy clusters (and groups) are rich in metals, which have been synthesised and released by asymptotic giant branch (AGB) stars, core-collapse supernovae (SNcc), and Type Ia supernovae (SNIa) over cosmic history. This makes the intracluster medium (ICM) an ideal astrophysical system to constrain its chemical composition, and hence ultimately understand metal production and enrichment on megaparsec scales.

Aims. In this work, we take advantage of the unprecedented ∼5 eV resolution offered by the Resolve instrument on board the XRISM observatory to measure the chemical composition of the core of the bright, nearby, and metal-rich Centaurus cluster with unprecedented accuracy. We use these measurements to provide constraints on the stellar populations having enriched the cluster core.

Methods. Through a deep (287 ks) Resolve full-array spectral analysis of Centaurus, we derived the Fe abundance and its relative Si/Fe, S/Fe, Ar/Fe, Ca/Fe, Cr/Fe, Mn/Fe, and Ni/Fe ratios. We completed this high-resolution view with N/Fe, O/Fe, Ne/Fe, and Mg/Fe ratios obtained with XMM-Newton/RGS archival data. This abundance pattern was then fitted with various combinations of AGBs, SNcc and SNIa nucleosynthesis yields with the aim of constraining their explosion and/or progenitor models.

Results. Similarly to the core of Perseus (from previous Hitomi/SXS results), we find that nine out of our 11 measured abundance ratios are formally consistent with the chemical composition of our Solar System (within uncertainties of the latter). However, the (super-solar) N/Fe and (half-solar) Mg/Fe ratios significantly differ from Perseus and/or other systems, and thus they provide tension with the picture of a fully solar composition ubiquitous to all systems. In addition, possible uncertainties in O/Fe and Ne/Fe with atomic codes highlight the need for studying more systems at high spectral resolution to assess (or rule out) the universality of the ICM composition in clusters’ cool cores. Combinations of (AGB+)SNcc+SNIa yield models can reproduce our observed X/Fe ratios in all cases. However, whether two distinct populations of SNIa are needed depends on the weight of our RGS measurements. We also briefly discuss the possibility of a multi-metallicity gas phase in this respect.