The COSMOS-Web deep galaxy group catalog up to z = 3.7

¹ Dipartimento di Fisica e Astronomia “A. Righi”, Alma Mater Studiorum Università di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
² INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 93/3, 40129 Bologna, Italy
³ Zentrum für Astronomie, Universität Heidelberg, Philosophenweg 12, 69120 Heidelberg, Germany
⁴ Department of Computer Science, Aalto University, PO Box 15400 00076 Espoo, Finland
⁵ Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2, 00560 Helsinki, Finland
⁶ ITP, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany
⁷ INFN – Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
⁸ CEA, IRFU, DAp, AIM, Université Paris-Saclay, Université Paris Cité, Sorbonne Paris Cité, CNRS, 91191 Gif-sur-Yvette, France
⁹ The University of Texas at Austin, 2515 Speedway Blvd Stop C1400, Austin, TX 78712, USA
¹⁰ Cosmic Dawn Center (DAWN), Copenhagen, Denmark
¹¹ Laboratory for Multiwavelength Astrophysics, School of Physics and Astronomy, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623, USA
¹² Niels Bohr Institute, University of Copenhagen, Jagtvej 128, DK-2200 Copenhagen, Denmark
¹³ Aix Marseille Univ., CNRS, CNES, LAM, Marseille, France
¹⁴ Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
¹⁵ Infosys Visiting Chair Professor, Department of Physics, Indian Institute of Science, Bangalore 560012, India
¹⁶ Instituto de Física y Astronomía, Universidad de Valparaíso, Avda. Gran Bretaña 1111, Valparaíso, Chile
¹⁷ DTU-Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Kgs. Lyngby, Denmark
¹⁸ Department of Physics & Astronomy, University of Hawaii at Hilo, 200 W. Kawili Street, Hilo, HI 96720, USA
¹⁹ Caltech/IPAC, MS 314-6, 1200 E. California Blvd., Pasadena, CA 91125, USA
²⁰ Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, USA
²¹ TU Dresden, Institute of Nuclear and Particle Physics, 01062 Dresden, Germany
²² DESY, Notkestrasse 85, 22607 Hamburg, Germany
²³ Deutsches Zentrum für Astrophysik, Postplatz 1, 02826 Görlitz, Germany
²⁴ Astrophysics Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
²⁵ Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218, USA
²⁶ Purple Mountain Observatory, Chinese Academy of Sciences, 10 Yuanhua Road, Nanjing 210023, China
²⁷ Department of Physics, Centre for Extragalactic Astronomy, Durham University, South Road, Durham DH1 3LE, UK
²⁸ Institut d’Astrophysique de Paris, UMR 7095, CNRS, and Sorbonne Université, 98 bis Boulevard Arago, F-75014 Paris, France
²⁹ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena CA 91001, USA
³⁰ Department of Astronomy and Astrophysics, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
³¹ International Space Science Institute (ISSI), Hallerstr. 6, CH-3012 Bern, Switzerland
³² National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
³³ Department of Physics and Astronomy, University of California, Riverside, 900 University Ave, Riverside, CA 92521, USA
³⁴ Tartu Observatory, University of Tartu, Observatooriumi 1, 61602 Tõravere, Estonia
³⁵ Thüringer Landessternwarte, Sternwarte 5, 07778 Tautenburg, Germany

^⋆ Corresponding author: greta.toni4@unibo.it

Received: 15 January 2025
Accepted: 27 March 2025

Abstract

Context. Galaxy groups with total masses below ∼10¹⁴ M_⊙ and up to a few tens of members are the most common galaxy environment, marking the transition between the field and the most massive galaxy clusters. In this framework, identifying and studying groups plays a crucial role in understanding structure formation and galaxy evolution. Despite the challenges in detecting such relatively small structures, modern deep surveys allow us to build well-characterized samples of galaxy groups up to the regime where the structures we observe today were taking shape.

Aims. We aim to build the largest deep catalog of galaxy groups to date over the COSMOS-Web field effective area of 0.45 deg².

Methods. We leveraged the deep imaging, high resolution, and high-quality photometry from the James Webb Space Telescope observations of the COSMOS-Web field. We used the recent COSMOS-Web photometric catalog with sky position, photometric redshift, and magnitude in a reference band for each selected galaxy. We performed the group search with the Adaptive Matched Identifier of Clustered Objects (AMICO) algorithm, a linear matched filter based on an analytical model for the cluster/group signal. This algorithm has already been tested in wide and deep field surveys, including a successful application to COSMOS data up to z = 2. In this work, we tested the algorithm’s performances at even higher redshift and searched for protocluster cores and groups at z > 2. To benchmark this relatively unexplored regime, we compiled a list of known protoclusters in COSMOS at 2 ≤ z ≤ 3.7 and matched them with our detections. We studied the spatial connection between detected cores through a clustering analysis. We estimated the purity and the completeness of our group sample by creating data-driven mocks via a Monte Carlo approach with the SinFoniA code and linked signal-to-noise to purity levels to define desired purity thresholds.

Results. We detected 1678 groups in the COSMOS-Web field up to z = 3.7 with a purity level of ∼77%, providing a deep catalog of galaxy members that extends nearly two magnitudes deeper than the previous application of AMICO to COSMOS. Around 670 groups have been detected with a purity of 90%. Our catalog includes more than 850 groups whose photometric redshift was confirmed by assigning robust spectroscopic counterparts.

Conclusions. This catalog of galaxy groups is the largest ultra-deep group sample built on JWST observations so far and offers a unique opportunity to explore several aspects of galaxy evolution in different environments spanning ∼12 Gyr and study groups themselves, from the least rich population of groups to the formation of the most massive clusters.