Iron in X-COP: Tracing enrichment in cluster outskirts with high accuracy abundance profiles

¹ INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano, Via A. Corti 12, 20133 Milano, Italy
e-mail: simona.ghizzardi@inaf.it
² European Southern Observatory, Karl-Schwarzschild Str. 2, 85748 Garching bei Muenchen, Germany
³ INAF – Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate, LC, Italy
⁴ Institute of Fundamental Physics of the Universe, Via Beirut 2, 34151 Grignano, Trieste, Italy
⁵ Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
⁶ Universitäts-Sternwarte München, Scheinerstr. 1, 81679 München, Germany
⁷ Dipartimento di Fisica, Sezione di Astronomia, Università di Trieste, Via Tiepolo 11, 34143 Trieste, Italy
⁸ INAF-Osservatorio Astronomico Trieste, Via Tiepolo 11, 34123 Trieste, Italy
⁹ INFN, Instituto Nazionale di Fisica Nucleare, Trieste, Italy
¹⁰ Department of Astronomy, University of Geneva, Ch. d’Ecogia 16, 1290 Versoix, Switzerland
¹¹ INAF–Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy
¹² INFN, Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
¹³ Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544, USA
¹⁴ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA

Received: 26 May 2020
Accepted: 12 October 2020

Abstract

We present the first metal abundance profiles for a representative sample of massive clusters. Our measurements extend to R₅₀₀ and are corrected for a systematic error plaguing previous outskirt estimates. Our profiles flatten out at large radii, admittedly not a new result, however the radial range and representative nature of our sample extends its import well beyond previous findings. We find no evidence of segregation between cool-core and non-cool-core systems beyond ∼0.3 R₅₀₀, implying that, as was found for thermodynamic properties, the physical state of the core does not affect global cluster properties. Our mean abundance within R₅₀₀ shows a very modest scatter, < 15%, suggesting the enrichment process must be quite similar in all these massive systems. This is a new finding and has significant implications for feedback processes. Together with results from the thermodynamic properties presented in a previous X-COP paper, it affords a coherent picture in which feedback effects do not vary significantly from one system to another. By combining intra-cluster medium with stellar measurements we have found the amount of Fe diffused in the intra-cluster medium to be about ten times higher than that locked in stars. Although our estimates suggest, with some strength, that the measured iron mass in clusters is well in excess of the predicted one, systematic errors prevent us from making a definitive statement. Further advancements will only be possible when systematic uncertainties, principally those associated with stellar masses, both within and beyond R₅₀₀, can be reduced.