Euclid preparation

LXXV. Estimating galaxy physical properties using CatBoost chained regressors with attention

¹ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
² DTx – Digital Transformation CoLAB, Building 1, Azurém Campus, University of Minho, 4800-058 Guimarães, Portugal
³ Faculdade de Ciências da Universidade do Porto, Rua do Campo de Alegre, 4150-007 Porto, Portugal
⁴ INAF, Istituto di Radioastronomia, Via Piero Gobetti 101, 40129 Bologna, Italy
⁵ Dipartimento di Fisica e Astronomia “G. Galilei”, Università di Padova, Via Marzolo 8, 35131 Padova, Italy
⁶ INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy
⁷ INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy
⁸ Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, 9000 Gent, Belgium
⁹ INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy
¹⁰ School of Mathematics and Physics, University of Surrey, Guildford, Surrey GU2 7XH, UK
¹¹ SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste TS, Italy
¹² INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy
¹³ INFN, Sezione di Trieste, Via Valerio 2, 34127 Trieste TS, Italy
¹⁴ IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy
¹⁵ Dipartimento di Fisica e Astronomia, Università di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
¹⁶ INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
¹⁷ Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany
¹⁸ INAF – Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese (TO), Italy
¹⁹ Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy
²⁰ INFN-Sezione di Genova, Via Dodecaneso 33, 16146 Genova, Italy
²¹ Department of Physics “E. Pancini”, University Federico II, Via Cinthia 6, 80126 Napoli, Italy
²² INFN section of Naples, Via Cinthia 6, 80126 Napoli, Italy
²³ Dipartimento di Fisica, Università degli Studi di Torino, Via P. Giuria 1, 10125 Torino, Italy
²⁴ INFN-Sezione di Torino, Via P. Giuria 1, 10125 Torino, Italy
²⁵ INAF-IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy
²⁶ Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona), Spain
²⁷ Port d’Informació Científica, Campus UAB, C. Albareda s/n, 08193 Bellaterra (Barcelona), Spain
²⁸ Institute for Theoretical Particle Physics and Cosmology (TTK), RWTH Aachen University, 52056 Aachen, Germany
²⁹ INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy
³⁰ Dipartimento di Fisica e Astronomia “Augusto Righi” – Alma Mater Studiorum Università di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy
³¹ Dipartimento di Fisica e Astronomia “Augusto Righi” – Alma Mater Studiorum Università di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
³² Instituto de Astrofísica de Canarias, Calle Vía Láctea s/n, 38204, San Cristóbal de La Laguna, Tenerife, Spain
³³ Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
³⁴ Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
³⁵ European Space Agency/ESRIN, Largo Galileo Galilei 1, 00044 Frascati, Roma, Italy
³⁶ ESAC/ESA, Camino Bajo del Castillo, s/n, Urb. Villafranca del Castillo, 28692 Villanueva de la Cañada, Madrid, Spain
³⁷ Université Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, Villeurbanne 69100, France
³⁸ Institute of Physics, Laboratory of Astrophysics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland
³⁹ UCB Lyon 1, CNRS/IN2P3, IUF, IP2I Lyon, 4 rue Enrico Fermi, 69622 Villeurbanne, France
⁴⁰ Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Edifício C8, Campo Grande, 1749-016 Lisboa, Portugal
⁴¹ Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
⁴² Department of Astronomy, University of Geneva, ch. d’Ecogia 16, 1290 Versoix, Switzerland
⁴³ INFN-Padova, Via Marzolo 8, 35131 Padova, Italy
⁴⁴ INAF – Istituto di Astrofisica e Planetologia Spaziali, via del Fosso del Cavaliere 100, 00100 Roma, Italy
⁴⁵ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
⁴⁶ Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität München, Scheinerstrasse 1, 81679 München, Germany
⁴⁷ Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, Via Irnerio 46, 40126 Bologna, Italy
⁴⁸ INAF-Osservatorio Astronomico di Padova, Via dell’Osservatorio 5, 35122 Padova, Italy
⁴⁹ Dipartimento di Fisica “Aldo Pontremoli”, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy
⁵⁰ INFN-Sezione di Milano, Via Celoria 16, 20133 Milano, Italy
⁵¹ Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, 0315 Oslo, Norway
⁵² Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
⁵³ Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
⁵⁴ von Hoerner & Sulger GmbH, Schlossplatz 8, 68723 Schwetzingen, Germany
⁵⁵ Technical University of Denmark, Elektrovej 327, 2800 Kgs. Lyngby, Denmark
⁵⁶ Cosmic Dawn Center (DAWN), Denmark
⁵⁷ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁵⁸ Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
⁵⁹ Department of Physics and Helsinki Institute of Physics, Gustaf Hällströmin katu 2, 00014 University of Helsinki, Finland
⁶⁰ Aix-Marseille Université, CNRS/IN2P3, CPPM, Marseille, France
⁶¹ Université de Genève, Département de Physique Théorique and Centre for Astroparticle Physics, 24 quai Ernest-Ansermet, CH-1211 Genève 4, Switzerland
⁶² Department of Physics, PO Box 64, 00014 University of Helsinki, Finland
⁶³ Helsinki Institute of Physics, Gustaf Hällströmin katu 2, University of Helsinki, Helsinki, Finland
⁶⁴ NOVA optical infrared instrumentation group at ASTRON, Oude Hoogeveensedijk 4, 7991PD, Dwingeloo, The Netherlands
⁶⁵ Centre de Calcul de l’IN2P3/CNRS, 21 avenue Pierre de Coubertin 69627 Villeurbanne Cedex, France
⁶⁶ Universität Bonn, Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn, Germany
⁶⁷ INFN-Sezione di Roma, Piazzale Aldo Moro 2, c/o Dipartimento di Fisica, Edificio G. Marconi, 00185 Roma, Italy
⁶⁸ Aix-Marseille Université, CNRS, CNES, LAM, Marseille, France
⁶⁹ Department of Physics, Centre for Extragalactic Astronomy, Durham University, South Road DH1 3LE, UK
⁷⁰ Institut d’Astrophysique de Paris, UMR 7095, CNRS, and Sorbonne Université, 98 bis boulevard Arago, 75014 Paris, France
⁷¹ Université Paris Cité, CNRS, Astroparticule et Cosmologie, 75013 Paris, France
⁷² University of Applied Sciences and Arts of Northwestern Switzerland, School of Engineering, 5210 Windisch, Switzerland
⁷³ Institut d’Astrophysique de Paris, 98bis Boulevard Arago, 75014 Paris, France
⁷⁴ European Space Agency/ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
⁷⁵ School of Mathematics, Statistics and Physics, Newcastle University, Herschel Building, Newcastle-upon-Tyne NE1 7RU, UK
⁷⁶ Department of Physics, Institute for Computational Cosmology, Durham University, South Road DH1 3LE, UK
⁷⁷ Department of Physics and Astronomy, University of Aarhus, Ny Munkegade 120, 8000 Aarhus C, Denmark
⁷⁸ Space Science Data Center, Italian Space Agency, via del Politecnico snc, 00133 Roma, Italy
⁷⁹ Centre National d’Etudes Spatiales – Centre spatial de Toulouse, 18 avenue Edouard Belin, 31401 Toulouse Cedex 9, France
⁸⁰ Institute of Space Science, Str. Atomistilor, nr. 409 Măgurele, Ilfov 077125, Romania
⁸¹ Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
⁸² Institut für Theoretische Physik, University of Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany
⁸³ Institut de Recherche en Astrophysique et Planétologie (IRAP), Université de Toulouse, CNRS, UPS, CNES, 14 Av. Edouard Belin, 31400 Toulouse, France
⁸⁴ Université St Joseph; Faculty of Sciences, Beirut, Lebanon
⁸⁵ Departamento de Física, FCFM, Universidad de Chile, Blanco Encalada 2008, Santiago, Chile
⁸⁶ Universität Innsbruck, Institut für Astro- und Teilchenphysik, Technikerstr. 25/8, 6020 Innsbruck, Austria
⁸⁷ Institut d’Estudis Espacials de Catalunya (IEEC), Edifici RDIT, Campus UPC, 08860 Castelldefels, Barcelona, Spain
⁸⁸ Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
⁸⁹ Satlantis, University Science Park, Sede Bld 48940, Leioa-Bilbao, Spain
⁹⁰ Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Avenida Complutense 40, 28040 Madrid, Spain
⁹¹ Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências, Universidade de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal
⁹² Universidad Politécnica de Cartagena, Departamento de Electrónica y Tecnología de Computadoras, Plaza del Hospital 1, 30202 Cartagena, Spain
⁹³ INFN-Bologna, Via Irnerio 46, 40126 Bologna, Italy
⁹⁴ Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA
⁹⁵ Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA), Loc. Lignan 39, 11020 Nus (Aosta Valley), Italy
⁹⁶ Junia, EPA department, 41 Bd Vauban, 59800 Lille, France
⁹⁷ ICSC – Centro Nazionale di Ricerca in High Performance Computing, Big Data e Quantum Computing, Via Magnanelli 2, Bologna, Italy
⁹⁸ Instituto de Física Teórica UAM-CSIC, Campus de Cantoblanco, 28049 Madrid, Spain
⁹⁹ CERCA/ISO, Department of Physics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
¹⁰⁰ Laboratoire Univers et Théorie, Observatoire de Paris, Université PSL, Université Paris Cité, CNRS, 92190 Meudon, France
¹⁰¹ Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, Via Giuseppe Saragat 1, 44122 Ferrara, Italy
¹⁰² Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara, Via Giuseppe Saragat 1, 44122 Ferrara, Italy
¹⁰³ Dipartimento di Fisica – Sezione di Astronomia, Università di Trieste, Via Tiepolo 11, 34131 Trieste, Italy
¹⁰⁴ Minnesota Institute for Astrophysics, University of Minnesota, 116 Church St SE, Minneapolis, MN 55455, USA
¹⁰⁵ Institute Lorentz, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
¹⁰⁶ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Bd de l’Observatoire, CS 34229, 06304 Nice cedex 4, France
¹⁰⁷ Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
¹⁰⁸ Department of Physics & Astronomy, University of California Irvine, Irvine, CA 92697, USA
¹⁰⁹ Department of Astronomy & Physics and Institute for Computational Astrophysics, Saint Mary’s University, 923 Robie Street, Halifax, Nova Scotia B3H 3C3, Canada
¹¹⁰ Departamento Física Aplicada, Universidad Politécnica de Cartagena, Campus Muralla del Mar, 30202 Cartagena, Murcia, Spain
¹¹¹ Department of Physics, Oxford University, Keble Road, Oxford OX1 3RH, UK
¹¹² Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, UK
¹¹³ Department of Computer Science, Aalto University, PO Box 15400, Espoo 00 076, Finland
¹¹⁴ Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute (AIRUB), German Centre for Cosmological Lensing (GCCL), 44780 Bochum, Germany
¹¹⁵ DARK, Niels Bohr Institute, University of Copenhagen, Jagtvej 155, 2200 Copenhagen, Denmark
¹¹⁶ Department of Physics and Astronomy, Vesilinnantie 5, 20014 University of Turku, Finland
¹¹⁷ Serco for European Space Agency (ESA), Camino bajo del Castillo, s/n, Urbanizacion Villafranca del Castillo, Villanueva de la Cañada, 28692 Madrid, Spain
¹¹⁸ ARC Centre of Excellence for Dark Matter Particle Physics, Melbourne, Australia
¹¹⁹ Centre for Astrophysics & Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
¹²⁰ W.M. Keck Observatory, 65-1120 Mamalahoa Hwy, Kamuela, HI, USA
¹²¹ School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, UK
¹²² Department of Physics and Astronomy, University of the Western Cape, Bellville, Cape Town 7535, South Africa
¹²³ ICTP South American Institute for Fundamental Research, Instituto de Física Teórica, Universidade Estadual Paulista, São Paulo, Brazil
¹²⁴ Oskar Klein Centre for Cosmoparticle Physics, Department of Physics, Stockholm University, Stockholm 106 91, Sweden
¹²⁵ Astrophysics Group, Blackett Laboratory, Imperial College London, London SW7 2AZ, UK
¹²⁶ INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
¹²⁷ Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 2, 00185 Roma, Italy
¹²⁸ Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
¹²⁹ Université Paris-Saclay, CNRS, Institut d’astrophysique spatiale, 91405 Orsay, France
¹³⁰ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
¹³¹ Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3, 53, Avenue des Martyrs, 38000 Grenoble, France
¹³² Department of Astrophysics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
¹³³ Dipartimento di Fisica, Università degli studi di Genova, and INFN-Sezione di Genova, via Dodecaneso 33, 16146 Genova, Italy
¹³⁴ Theoretical astrophysics, Department of Physics and Astronomy, Uppsala University, Box 515, 751 20 Uppsala, Sweden
¹³⁵ Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
¹³⁶ Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544, USA
¹³⁷ Niels Bohr Institute, University of Copenhagen, Jagtvej 128, 2200 Copenhagen, Denmark
¹³⁸ Cosmic Dawn Center (DAWN)
¹³⁹ Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10003, USA
¹⁴⁰ Center for Computational Astrophysics, Flatiron Institute, 162 5th Avenue, New York, NY 10010, USA

^★ Corresponding author: andrew.humphrey@astro.up.pt

Received: 2 October 2024
Accepted: 14 April 2025

Abstract

The Euclid Space Telescope will image about 14 000 deg² of the extragalactic sky at visible and near-infrared wavelengths, providing a dataset of unprecedented size and richness that will facilitate a multitude of studies into the evolution of galaxies. Although spectroscopy will also be available for some of the galaxies, in the vast majority of cases the main source of information will come from broadband images and data products thereof (i.e. photometry). Therefore, there is a pressing need to identify or develop scalable yet reliable methodologies to estimate the redshift and physical properties of galaxies using broadband photometry from Euclid. Optionally, such methods could also include ground-based optical photometry. To address this need, we present a novel method developed as part of a ‘data challenge’ within the Euclid Collaboration to estimate the redshift, stellar mass, star-formation rate, specific star-formation rate, E(B − V), and age of galaxies using mock Euclid and ground-based photometry. The main novelty of our property-estimation pipeline is its use of the CatBoost implementation of gradient-boosted regression-trees together with chained regression and an intelligent, automatic optimisation of the training data. The pipeline also includes a computationally efficient method to estimate prediction uncertainties, and, in the absence of ground-truth labels, it provides accurate predictions for metrics of model performance up to z ~ 2. We applied our pipeline to several datasets consisting of mock Euclid broadband photometry and mock ground-based ugriz photometry, with the objective of evaluating the performance of our methodology for estimating the redshift and physical properties of galaxies detected in the Euclid Wide Survey. The statistical metrics of prediction residuals vary depending on which mock catalogue and filters are tested. Nonetheless, the quality of our photometric redshift and physical property estimates are highly competitive overall, validating our modelling approach. However, at z ≳ 3.5, the relative sparsity of galaxies resulted in unreliable redshift and physical property estimates, which we argue could be mitigated by building catalogues with better sampling of z ≳ 3.5 galaxies or by switching to the use of spectral energy distribution fitting in this regime. We also find that the inclusion of ground-based optical photometry significantly improves the quality of the property estimation, highlighting the importance of combining Euclid data with ancillary ground-based data from such surveys as the Vera C. Rubin Observatory Legacy Survey of Space and Time and UNIONS.