Euclid: Nonparametric point spread function field recovery through interpolation on a graph Laplacian
Astronomy and Astrophysics, vol. 636, pp. A78
Abstract
Context.Future weak lensing surveys, such as theEuclidmission, will attempt to measure the shapes of billions of galaxies in order to derive cosmological information. These surveys will attain very low levels of statistical error, and systematic errors must be extremely well controlled. In particular, the point spread function (PSF) must be estimated using stars in the field, and recovered with high accuracy. Aims.The aims of this paper are twofold. Firstly, we took steps toward a nonparametric method to address the issue of recovering the PSF field, namely that of finding the correct PSF at the position of any galaxy in the field, applicable toEuclid. Our approach relies solely on the data, as opposed to parametric methods that make use of our knowledge of the instrument. Secondly, we studied the impact of imperfect PSF models on the shape measurement of galaxies themselves, and whether common assumptions about this impact hold true in anEuclidscenario. Methods.We extended the recently proposed resolved components analysis approach, which performs super-resolution on a field of under-sampled observations of a spatially varying, image-valued function. We added a spatial interpolation component to the method, making it a true 2-dimensional PSF model. We compared our approach toPSFEx, then quantified the impact of PSF recovery errors on galaxy shape measurements through image simulations. Results.Our approach yields an improvement overPSFExin terms of the PSF model and on observed galaxy shape errors, though it is at present far from reaching the requiredEuclidaccuracy. We also find that the usual formalism used for the propagation of PSF model errors to weak lensing quantities no longer holds in the case of anEuclid-like PSF. In particular, different shape measurement approaches can react differently to the same PSF modeling errors.
Authors 17
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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, Via Piero Gobetti 93/3, 40129 Bologna, Italy
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Leiden University · Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto · Leiden Observatory
Affiliation as printed
Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333, CA Leiden, The Netherlands
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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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Osservatorio Astrofisico di Torino
Affiliation as printed
INAF-Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese (TO), Italy
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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
Affiliation as printed
Aix-Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France
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Trieste Astronomical Observatory
Affiliation as printed
INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34131 Trieste, Italy
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National Institute for Astrophysics
Affiliation as printed
INAF-IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy
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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
Affiliation as printed
Aix-Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France
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Affiliation as printed
Université de Genève, Département de Physique Théorique and Centre for Astroparticle Physics, 24 quai Ernest-Ansermet, 1211 Genève 4, Switzerland
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Osservatorio Astrofisico di Torino
Affiliation as printed
INAF-Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese (TO), Italy
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Affiliation as printed
Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, 0315 Oslo, Norway
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Affiliation as printed
Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
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Trieste Astronomical Observatory
Affiliation as printed
INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34131 Trieste, Italy
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Centre National de la Recherche Scientifique · Commissariat à l'Énergie Atomique et aux Énergies Alternatives · Université Paris-Saclay · Astrophysique, Instrumentation et Modélisation · Sorbonne Paris Cité · Université Paris Diderot
Affiliation as printed
AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France
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Max Planck Institute for Extraterrestrial Physics · Ludwig-Maximilians-Universität München
Affiliation as printed
Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany
Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität München, Scheinerstrasse 1, 81679 München, Germany
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Universidad Politécnica de Cartagena
Affiliation as printed
Depto. de Electrónica y Tecnología de Computadoras Universidad Politécnica de Cartagena, 30202 Cartagena, Spain
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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, Via Piero Gobetti 93/3, 40129 Bologna, Italy
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