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http://hdl.handle.net/20.500.12386/31474
Title: | Euclid: Nonparametric point spread function field recovery through interpolation on a graph Laplacian | Authors: | Schmitz, M. A. Starck, J. -L. Ngole Mboula, F. AURICCHIO, NATALIA Brinchmann, J. Vito Capobianco, R. I. Clédassou, R. Conversi, L. CORCIONE, Leonardo Fourmanoit, N. FRAILIS, Marco GARILLI, BIANCA MARIA ROSA Hormuth, F. Hu, D. Israel, H. Kermiche, S. Kitching, T. D. Kubik, B. Kunz, M. LIGORI, Sebastiano Lilje, P. B. Lloro, I. MANSUTTI, Oriana Marggraf, O. Massey, R. J. PASIAN, Fabio Pettorino, V. Raison, F. Rhodes, J. D. Roncarelli, M. Saglia, R. P. Schneider, P. Serrano, S. Taylor, A. N. Toledo-Moreo, R. VALENZIANO, LUCA Vuerli, C. Zoubian, J. |
Issue Date: | 2020 | Journal: | ASTRONOMY & ASTROPHYSICS | Number: | 636 | First Page: | A78 | Abstract: | Context. Future weak lensing surveys, such as the Euclid mission, 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 to Euclid. 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 an Euclid scenario. 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 to PSFEx, then quantified the impact of PSF recovery errors on galaxy shape measurements through image simulations. Results: Our approach yields an improvement over PSFEx in terms of the PSF model and on observed galaxy shape errors, though it is at present far from reaching the required Euclid accuracy. 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 an Euclid-like PSF. In particular, different shape measurement approaches can react differently to the same PSF modeling errors. | Acknowledgments: | The Euclid PSFs used in this work were provided by Koryo Okumura, Samuel Ronayette and Jérôme Amiaux. The authors are grateful to Lance Miller, Henk Hoekstra and Christopher Duncan for their comments on an earlier draft of this paper, to the anonymous, external referee for their comments and suggestions, to Arnau Pujol and Florent Sureau for numerous helpful discussions and advice on shape measurement, and to Imane El Hamzaoui for her help with some of the figures in this paper. This work was supported by the Centre National d’Etudes Spatiales and the European Community through the grant DEDALE (contract no. 665044) within the H2020 Framework Program. JB acknowledges support by Fundação para a Ciência e a Tecnologia through national funds (UID/FIS/04434/2013) and Investigador FCT contract IF/01654/2014/CP1215/CT0003, and by FEDER through COMPETE2020 (POCI-01-0145-FEDER-007672). The authors acknowledge the Euclid Consortium, the European Space Agency and the support of a number of agencies and institutes that have supported the development of Euclid. A detailed complete list is available on the Euclid web site (http://www. euclid-ec.org). In particular the Academy of Finland, the Agenzia Spaziale Italiana, the Belgian Science Policy, the Canadian Euclid Consortium, the Centre National d’Etudes Spatiales, the Deutsches Zentrum für Luft- and Raumfahrt, the Danish Space Research Institute, the Fundação para a Ciênca e a Tecnologia, the Ministerio de Economia y Competitividad, the National Aeronautics and Space Administration, the Netherlandse Onderzoekschool Voor Astronomie, the Norvegian Space Center, the Romanian Space Agency, the State Secretariat for Education, Research and Innovation (SERI) at the Swiss Space Office (SSO), and the United Kingdom Space Agency. | URI: | http://hdl.handle.net/20.500.12386/31474 | URL: | https://www.aanda.org/articles/aa/full_html/2020/04/aa36094-19/aa36094-19.html | ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/201936094 | Bibcode ADS: | 2020A&A...636A..78S | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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