Euclid Quick Data Release (Q1). From simulations to sky: Advancing machine-learning lens detection with real Euclid data
HAL (Le Centre pour la Communication Scientifique Directe)
Abstract
In the era of large-scale surveys like Euclid, machine learning has become an essential tool for identifying rare yet scientifically valuable objects, such as strong gravitational lenses. However, supervised machine-learning approaches require large quantities of labelled examples to train on, and the limited number of known strong lenses has lead to a reliance on simulations for training. A well-known challenge is that machine-learning models trained on one data domain often underperform when applied to a different domain: in the context of lens finding, this means that strong performance on simulated lenses does not necessarily translate into equally good performance on real observations. In Euclid's Quick Data Release 1 (Q1), covering 63 deg2, 500 strong lens candidates were discovered through a synergy of machine learning, citizen science, and expert visual inspection. These discoveries now allow us to quantify this performance gap and investigate the impact of training on real data. We find that a network trained only on simulations recovers up to 92% of simulated lenses with 100% purity, but only achieves 50% completeness with 24% purity on real Euclid data. By augmenting training data with real Euclid lenses and non-lenses, completeness improves by 25-30% in terms of the expected yield of discoverable lenses in Euclid DR1 and the full Euclid Wide Survey. Roughly 20% of this improvement comes from the inclusion of real lenses in the training data, while 5-10% comes from exposure to a more diverse set of non-lenses and false-positives from Q1. We show that the most effective lens-finding strategy for real-world performance combines the diversity of simulations with the fidelity of real lenses. This hybrid approach establishes a clear methodology for maximising lens discoveries in future data releases from Euclid, and will likely also be applicable to other surveys such as LSST.
Authors 48
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Affiliation as printed
Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, UK
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FHNW University of Applied Sciences and Arts Northwestern Switzerland
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University of Applied Sciences and Arts of Northwestern Switzerland, School of Computer Science, 5210 Windisch, Switzerland
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Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics · University of Bologna
Affiliation as printed
Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Università di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy
INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy
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Affiliation as printed
Department of Physics, Oxford University, Keble Road, Oxford OX1 3RH, UK
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Centre National de la Recherche Scientifique · Aix-Marseille Université · Institut d'Astrophysique de Paris · Sorbonne Université
Affiliation as printed
Aix-Marseille Université, CNRS, CNES, LAM, Marseille, France
Institut d'Astrophysique de Paris, UMR 7095, CNRS, and Sorbonne Université, 98 bis boulevard Arago, 75014 Paris, France
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European Space Astronomy Centre
Affiliation as printed
ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo, 28692 Villanueva de la Cañada, Madrid, Spain
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Affiliation as printed
Institut für Theoretische Physik, University of Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany
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Brera Astronomical Observatory
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INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy
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Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics
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INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy
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Scuola Internazionale Superiore di Studi Avanzati · Trieste Astronomical Observatory · Istituto Nazionale di Fisica Nucleare, Sezione di Trieste · Institute for Fundamental Physics of the Universe
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IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy
INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy
INFN, Sezione di Trieste, Via Valerio 2, 34127 Trieste TS, Italy
SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste TS, Italy
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Istituto Nazionale di Fisica Nucleare, Sezione di Bologna · Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics · University of Bologna
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Dipartimento di Fisica e Astronomia, Università di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy
INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
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Osservatorio Astronomico di Padova
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INAF-Osservatorio Astronomico di Padova, Via dell'Osservatorio 5, 35122 Padova, Italy
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Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics
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INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy
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Trieste Astronomical Observatory · Institute for Fundamental Physics of the Universe
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INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy
IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy
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Brera Astronomical Observatory · Istituto Nazionale di Fisica Nucleare, Sezione di Genova · University of Genoa
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Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146, Genova, Italy
INFN-Sezione di Genova, Via Dodecaneso 33, 16146, Genova, Italy
INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy
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Istituto Nazionale di Fisica Nucleare, Sezione di Torino · Osservatorio Astrofisico di Torino · University of Turin · National Institute for Astrophysics
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Dipartimento di Fisica, Università degli Studi di Torino, Via P. Giuria 1, 10125 Torino, Italy
INFN-Sezione di Torino, Via P. Giuria 1, 10125 Torino, Italy
INAF-Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese
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Port d'Informació Científica · Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas
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Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas
Port d'Informació Científica, Campus UAB, C. Albareda s/n, 08193 Bellaterra
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Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics
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INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy
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Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Università di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
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Instituto de Astrofísica de Canarias
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Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain
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Royal Observatory · University of Edinburgh
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Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
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Department of Astronomy, University of Geneva, ch. d'Ecogia 16, 1290 Versoix, Switzerland
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European Space Astronomy Centre
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ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo, 28692 Villanueva de la Cañada, Madrid, Spain
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Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
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INAF-Istituto di Astrofisica e Planetologia Spaziali, via del Fosso del Cavaliere, 100, 00100 Roma, Italy
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Astronomical Observatory of Rome · Agenzia Spaziale Italiana · Institut de Physique des 2 Infinis de Lyon · National Institute for Astrophysics
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Space Science Data Center, Italian Space Agency, via del Politecnico snc, 00133 Roma, Italy
IP2I Lyon - Institut de Physique des 2 Infinis de Lyon (Campus LyonTech-la Doua Bâtiment Paul DIRAC 4 Rue Enrico Fermi 69622 Villeurbanne Cedex - France)
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Lyon 1 Université · Centre National de la Recherche Scientifique · Institut National de Physique Nucléaire et de Physique des Particules · Institut de Physique des 2 Infinis de Lyon
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Université Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, Villeurbanne, F-69100, France
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Istituto Nazionale di Fisica Nucleare, Sezione di Bologna · Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics
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Ludwig-Maximilians-Universität München
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Royal Observatory · University of Edinburgh
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Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
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European Space Astronomy Centre
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FRACTAL S.L.N.E., calle Tulipán 2, Portal 13 1A, 28231, Las Rozas de Madrid, Spain
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Max Planck Institute for Extraterrestrial Physics
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Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany
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Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
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Felix Hormuth Engineering, Goethestr. 17, 69181 Leimen, Germany
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Technical University of Denmark
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Technical University of Denmark, Elektrovej 327, 2800 Kgs. Lyngby, Denmark
Cosmic Dawn Center
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Max Planck Institute for Astronomy
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Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
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NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
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Centre National de la Recherche Scientifique · Aix-Marseille Université · Centre de physique des particules de Marseille · Institut National de Physique Nucléaire et de Physique des Particules
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Aix-Marseille Université, CNRS/IN2P3, CPPM, Marseille, France
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Jet Propulsion Laboratory · Institut de Physique des 2 Infinis de Lyon
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Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, 91109, USA
IP2I Lyon - Institut de Physique des 2 Infinis de Lyon (Campus LyonTech-la Doua Bâtiment Paul DIRAC 4 Rue Enrico Fermi 69622 Villeurbanne Cedex - France)
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Université de Genève, Département de Physique Théorique and Centre for Astroparticle Physics, 24 quai Ernest-Ansermet, CH-1211 Genève 4, Switzerland
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University of Helsinki · Helsinki Institute of Physics · Laboratoire d'Étude de l'Univers et des Phénomènes Extrêmes
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University of Milan · Istituto Nazionale di Fisica Nucleare, Sezione di Milano · National Institute for Astrophysics
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Trieste Astronomical Observatory
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Aix-Marseille Université, CNRS, CNES, LAM, Marseille, France
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Osservatorio di Astrofisica e Scienza dello Spazio · Université Paris Diderot · Centre Pierre Binétruy · National Institute for Astrophysics · University of California, Berkeley
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CPB - Centre Pierre Binétruy (UNIVERSITY OF CALIFORNIA BERKELEY - Berkeley, Physics Department 00366 LeConte Hall - United States)
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Centre National de la Recherche Scientifique · Université Paris Cité · Institut National de Physique Nucléaire et de Physique des Particules · Centre Pierre Binétruy · University of California, Berkeley
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CNRS-UCB International Research Laboratory, Centre Pierre Binétruy, IRL2007, CPB-IN2P3, Berkeley, USA
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