Thermal Sunyaev-Zel’dovich effect at the core of CL J1226.9+3332 revealed by NOEMA

¹ IRAP, CNRS, Université de Toulouse, CNES, UT3-UPS, (Toulouse), France
² Université Grenoble Alpes, CNRS, LPSC-IN2P3, 53, avenue des Martyrs, 38000 Grenoble, France
³ Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38406 Saint-Martin-d’Hères, France
⁴ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, France
⁵ School of Physics and Astronomy, Cardiff University, Queen’s Buildings, The Parade, Cardiff CF24 3AA, UK
⁶ Université Paris Cité, Université Paris-Saclay, CEA, CNRS, AIM, F-91191 Gif-sur-Yvette, France
⁷ Institut de Radioastronomie Millimétrique (IRAM), Avenida Divina Pastora 7, Local 20, E-18012 Granada, Spain
⁸ Aix Marseille Univ, CNRS, CNES, LAM (Laboratoire d’Astrophysique de Marseille), Marseille, France
⁹ Institut Néel, CNRS, Université Grenoble Alpes, France
¹⁰ Université de Strasbourg, CNRS, Observatoire astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France
¹¹ Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 5, I-00185 Roma, Italy
¹² Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
¹³ Institute for Research in Fundamental Sciences (IPM), School of Astronomy, Tehran, Iran
¹⁴ Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, 28850 Madrid, Spain
¹⁵ Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France
¹⁶ National Observatory of Athens, Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, Ioannou Metaxa and Vasileos Pavlou, GR-15236 Athens, Greece
¹⁷ Department of Astrophysics, Astronomy & Mechanics, Faculty of Physics, University of Athens, Panepistimiopolis, GR-15784 Zografos, Athens, Greece
¹⁸ High Energy Physics Division, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439, USA
¹⁹ LUX, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Université, UPMC, 75014 Paris, France
²⁰ Institute of Space Sciences (ICE), CSIC, Campus UAB, Carrer de Can Magrans s/n, E-08193 Barcelona, Spain
²¹ ICREA, Pg. Lluís Companys 23, Barcelona, Spain
²² Dipartimento di Fisica, Università di Roma ‘Tor Vergata’, Via della Ricerca Scientifica 1, I-00133 Roma, Italy
²³ School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
²⁴ Institut d’Astrophysique de Paris, CNRS (UMR7095), 98 bis boulevard Arago, 75014 Paris, France
²⁵ University of Lyon, UCB Lyon 1, CNRS/IN2P3, IP2I, 69622 Villeurbanne, France
²⁶ INAF, IASF-Milano, Via A. Corti 12, 20133 Milano, Italy
²⁷ IRFU, CEA, Université Paris-Saclay, 91191 Gif-sur-Yvette, France

^⋆ Corresponding author: miren.munoz-echeverria@irap.omp.eu

Received: 6 June 2025
Accepted: 11 September 2025

Abstract

We present first detailed maps of the thermal Sunyaev-Zel’dovich (tSZ) effect on a z = 0.89 cluster with the NOrthern Extended Millimeter Array (NOEMA). The high sensitivity of these observations enabled the effective identification and removal of the millimetre-wave sources contaminating the tSZ signal, thus isolating the influence of the hot electron gas of the cluster on the cosmic microwave background radiation from other emissions. The tSZ observed with success by NOEMA was modelled together with previous single-dish observations (IRAM 30-metre, Green Bank Telescope, and Caltech Sub-millimeter Observatory) to obtain the first core-to-outskirts (from ∼15 to ∼1500 kpc) pressure profile reconstruction on such a high-redshift galaxy cluster. NOEMA observations with a high angular resolution have shown that the pressure profile is flat in the core of the cluster. These observations confirm the disturbed nature of CL J1226.9+3332 and map for the first time the distribution of its thermal gas at arcsecond scales in the environments of the central cluster galaxy. Our results showcase the excellent capabilities of NOEMA to complement and enhance the data provided by other millimetre-wave instruments in resolving the core of high-redshift clusters via tSZ emission.