Euclid : Improving redshift distribution reconstruction using a deep-to-wide transfer function
Astronomy and Astrophysics, vol. 709, pp. A55
Abstract
The Euclid mission of the European Space Agency seeks to understand the Universe’s expansion history and the nature of dark energy, through measurements of cosmic shear. This requires a very accurate estimate of the true redshift distribution of the galaxies, with the systematic error in the mean redshift satisfying σ ⟨ z ⟩ < 0.002(1 + z ) per tomographic bin. Achieving this accuracy relies on reference samples with spectroscopic redshifts, together with a procedure to match them to survey sources for which only photometric redshifts are available. One important source of systematic uncertainty is the mismatch in photometric properties between galaxies in the Euclid survey and the reference objects. We develop a method to degrade the photometry of objects with deep photometry to match the properties of any shallower survey in the multi-band photometric space, preserving all the correlations between the fluxes and their uncertainties. We compare our transfer method with more demanding image-based methods, such as Balrog from the Dark Energy Survey Collaboration. According to our metrics, our method outperforms Balrog. We implement our method in the redshift distribution reconstruction, based on the self-organising map approach, and test it using a realistic sample from the Euclid Flagship Mock Galaxy Simulation. We find that the key ingredient is to ensure that the reference objects are distributed in the colour space the same way as the wide-survey objects, which can be efficiently achieved with our transfer method. In our best implementation, the mean redshift biases are consistently reduced across the tomographic bins, bringing a significant fraction of them within the Euclid accuracy requirements in all tomographic bins. Equally importantly, the tests allow us to pinpoint which step in the calibration pipeline has the strongest impact on achieving the required accuracy. Our approach also reproduces the overall redshift distributions, which are crucial for applications such as angular clustering. The agreement between the reconstructed and true distributions demonstrates both the feasibility and robustness of the approach. This implementation is sufficient for Euclid Data Release 1 and provides a solid foundation for subsequent data releases.
Authors 100
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Affiliation as printed
Department of Astronomy, University of Geneva
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Affiliation as printed
Department of Astronomy, University of Geneva
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Affiliation as printed
Department of Astronomy, University of Geneva
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Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics
Affiliation as printed
INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna
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Affiliation as printed
Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute (AIRUB), German Centre for Cosmological Lensing (GCCL)
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Affiliation as printed
Department of Astronomy, University of Geneva
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Institute of Space Sciences · Institut d'Estudis Espacials de Catalunya · Universitat Politècnica de Catalunya
Affiliation as printed
Institut d’Estudis Espacials de Catalunya (IEEC), Edifici RDIT, Campus UPC
Institute of Space Sciences (ICE, CSIC), Campus UAB
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California Institute of Technology · Infrared Processing and Analysis Center
Affiliation as printed
Infrared Processing and Analysis Center, California Institute of Technology
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Institute for High Energy Physics · Barcelona Institute of Science and Technology
Affiliation as printed
Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB
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Affiliation as printed
Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute (AIRUB), German Centre for Cosmological Lensing (GCCL)
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Centre National de la Recherche Scientifique · Aix-Marseille Université
Affiliation as printed
Aix-Marseille Université, CNRS, CNES, LAM
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Universitat Autònoma de Barcelona · Institute for High Energy Physics · Barcelona Institute of Science and Technology
Affiliation as printed
Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB
Serra Húnter Fellow, Departament de Física, Universitat Autònoma de Barcelona
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Max Planck Institute for Extraterrestrial Physics
Affiliation as printed
Max Planck Institute for Extraterrestrial Physics
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Affiliation as printed
Department of Physics and Astronomy, University of California
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Centre National de la Recherche Scientifique · Université Paris-Saclay · Institut d'Astrophysique Spatiale
Affiliation as printed
Université Paris-Saclay, CNRS, Institut d’astrophysique spatiale
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European Space Agency · European Space Astronomy Centre
Affiliation as printed
ESAC/ESA
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Brera Astronomical Observatory · National Institute for Astrophysics
Affiliation as printed
INAF-Osservatorio Astronomico di Brera
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Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics
Affiliation as printed
INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna
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Centre National de la Recherche Scientifique · Université Paris Cité · Commissariat à l'Énergie Atomique et aux Énergies Alternatives · Université Paris-Saclay · Astrophysique, Instrumentation et Modélisation
Affiliation as printed
Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM
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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 · National Institute for Astrophysics
Affiliation as printed
IFPU, Institute for Fundamental Physics of the Universe
INAF-Osservatorio Astronomico di Trieste
INFN, Sezione di Trieste
SISSA, International School for Advanced Studies
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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
Affiliation as printed
Dipartimento di Fisica e Astronomia, Università di Bologna
INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna
INFN-Sezione di Bologna
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Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics
Affiliation as printed
INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna
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Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics
Affiliation as printed
INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna
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Trieste Astronomical Observatory · Institute for Fundamental Physics of the Universe · National Institute for Astrophysics
Affiliation as printed
IFPU, Institute for Fundamental Physics of the Universe
INAF-Osservatorio Astronomico di Trieste
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Brera Astronomical Observatory · Istituto Nazionale di Fisica Nucleare, Sezione di Genova · University of Genoa · National Institute for Astrophysics
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Dipartimento di Fisica, Università di Genova
INAF-Osservatorio Astronomico di Brera
INFN-Sezione di Genova
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Astronomical Observatory of Capodimonte · University of Naples Federico II · National Institute for Astrophysics
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Department of Physics “E. Pancini”, University Federico II
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European Southern Observatory · Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto · European Southern Observatory
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European Southern Observatory
Faculdade de Ciências da Universidade do Porto, Rua do Campo de Alegre
Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas
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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
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INFN-Sezione di Torino
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Leiden University · Royal Observatory · Leiden Observatory · University of Edinburgh
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Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill
Leiden Observatory, Leiden University
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Osservatorio Astrofisico di Torino · National Institute for Astrophysics
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INAF-Osservatorio Astrofisico di Torino
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National Institute for Astrophysics
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INAF-IASF Milano
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Astronomical Observatory of Rome · Istituto Nazionale di Fisica Nucleare, Sezione di Roma I · National Institute for Astrophysics
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INAF-Osservatorio Astronomico di Roma
INFN-Sezione di Roma
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Universitat Autònoma de Barcelona · Port d'Informació Científica · Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas
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Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT)
Port d’Informació Científica, Campus UAB
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Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) · RWTH Aachen University
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Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR), Linder Höhe
Institute for Theoretical Particle Physics and Cosmology (TTK), RWTH Aachen University
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Astronomical Observatory of Rome · National Institute for Astrophysics
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INAF-Osservatorio Astronomico di Roma
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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
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Istituto Nazionale di Fisica Nucleare · Astronomical Observatory of Capodimonte · Istituto Nazionale di Fisica Nucleare, Sezione di Napoli · National Institute for Astrophysics
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INAF-Osservatorio Astronomico di Capodimonte
INFN section of Naples
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University of Hawaiʻi at Mānoa · University of Hawaii System
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Institute for Astronomy, University of Hawaii
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Dipartimento di Fisica e Astronomia “Augusto Righi” – Alma Mater Studiorum Università di Bologna
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Instituto de Astrofísica de Canarias
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Instituto de Astrofísica de Canarias
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Royal Observatory · University of Edinburgh
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Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill
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European Space Agency · European Space Astronomy Centre · European Space Research Institute
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ESAC/ESA
European Space Agency/ESRIN
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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
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Centre National de la Recherche Scientifique · Aix-Marseille Université
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Aix-Marseille Université, CNRS, CNES, LAM
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Institució Catalana de Recerca i Estudis Avançats · Institute of Space Sciences · Consejo Superior de Investigaciones Científicas · Institut de Ciències del Cosmos · Universitat de Barcelona
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Institució Catalana de Recerca i Estudis Avançats (ICREA)
Institut de Ciencies de l’Espai (IEEC-CSIC), Campus UAB
Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona (IEEC-UB)
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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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UCB Lyon 1, CNRS/IN2P3, IUF, IP2I Lyon
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Affiliation as printed
Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking
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Department of Astronomy, University of Geneva
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Trieste Astronomical Observatory · National Institute for Astrophysics
Affiliation as printed
INAF-Osservatorio Astronomico di Trieste
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Centre National de la Recherche Scientifique · Université Paris-Saclay · Institut d'Astrophysique Spatiale
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Université Paris-Saclay, CNRS, Institut d’astrophysique spatiale
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Royal Observatory · University of Edinburgh
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Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill
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European Space Agency · European Space Astronomy Centre
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ESAC/ESA
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Istituto Nazionale di Fisica Nucleare · Istituto Nazionale di Fisica Nucleare, Sezione di Padova
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INFN-Padova
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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
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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
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Institute for Space Astrophysics and Planetology · National Institute for Astrophysics
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Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics
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Centre National de la Recherche Scientifique · Université Paris Cité · Commissariat à l'Énergie Atomique et aux Énergies Alternatives · Université Paris-Saclay · Astrophysique, Instrumentation et Modélisation
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Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM
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Astronomical Observatory of Rome · Agenzia Spaziale Italiana · National Institute for Astrophysics
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INAF-Osservatorio Astronomico di Roma
Space Science Data Center, Italian Space Agency
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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
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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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INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna
INFN-Bologna
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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
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Trieste Astronomical Observatory · National Institute for Astrophysics
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INAF-Osservatorio Astronomico di Trieste
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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
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National Institute for Astrophysics
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INAF-IASF Milano
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Trieste Astronomical Observatory · National Institute for Astrophysics
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INAF-Osservatorio Astronomico di Trieste
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Ludwig-Maximilians-Universität München
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University Observatory, LMU Faculty of Physics
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Royal Observatory · University of Edinburgh
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Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill
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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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INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna
INFN-Sezione di Bologna
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Max Planck Institute for Extraterrestrial Physics
Affiliation as printed
Max Planck Institute for Extraterrestrial Physics
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Osservatorio Astronomico di Padova · National Institute for Astrophysics
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INAF-Osservatorio Astronomico di Padova
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Max Planck Institute for Extraterrestrial Physics · Ludwig-Maximilians-Universität München
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Max Planck Institute for Extraterrestrial Physics
Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität München
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Affiliation as printed
Institute of Theoretical Astrophysics, University of Oslo
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Leiden University · Leiden Observatory
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Leiden Observatory, Leiden University
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Affiliation as printed
Jet Propulsion Laboratory, California Institute of Technology
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Affiliation as printed
Felix Hormuth Engineering
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Technical University of Denmark
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Cosmic Dawn Center (DAWN)
Technical University of Denmark
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Centre National de la Recherche Scientifique · Institut d'Astrophysique de Paris · Sorbonne Université
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Institut d’Astrophysique de Paris, UMR 7095, CNRS, and Sorbonne Université
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Max Planck Institute for Astronomy
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Max-Planck-Institut für Astronomie
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NASA Goddard Space Flight Center
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Department of Physics and Astronomy, University College London
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Affiliation as printed
Department of Physics and Helsinki Institute of Physics
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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
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Affiliation as printed
Jet Propulsion Laboratory, California Institute of Technology
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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
Affiliation as printed
Université Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822
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Ludwig-Maximilians-Universität München
Affiliation as printed
Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität München
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Affiliation as printed
Université de Genève, Département de Physique Théorique and Centre for Astroparticle Physics
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Department of Physics
Helsinki Institute of Physics
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Kapteyn Astronomical Institute, University of Groningen
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Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Observatoire de Paris · Sorbonne Université · Laboratoire d'Étude de l'Univers et des Phénomènes Extrêmes
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Laboratoire d’etude de l’Univers et des phenomenes eXtremes, Observatoire de Paris, Université PSL, Sorbonne Université, CNRS
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Osservatorio Astrofisico di Torino · National Institute for Astrophysics
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INAF-Osservatorio Astrofisico di Torino
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Affiliation as printed
Institute of Theoretical Astrophysics, University of Oslo
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Affiliation as printed
Department of Physics
Helsinki Institute of Physics
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Affiliation as printed
SKAO, Jodrell Bank, Lower Withington
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Centre National de la Recherche Scientifique · Centre de Calcul de l’Institut National de Physique Nucléaire et de Physique des Particules
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Centre de Calcul de l’IN2P3/CNRS
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University of Milan · Istituto Nazionale di Fisica Nucleare, Sezione di Milano · National Institute for Astrophysics
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Dipartimento di Fisica “Aldo Pontremoli”, Università degli Studi di Milano
INAF-IASF Milano
INFN-Sezione di Milano
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Osservatorio di Astrofisica e Scienza dello Spazio · National Institute for Astrophysics
Affiliation as printed
INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna
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Trieste Astronomical Observatory · National Institute for Astrophysics
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INAF-Osservatorio Astronomico di Trieste
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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
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Affiliation as printed
Universität Bonn, Argelander-Institut für Astronomie
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