Euclid preparation. LX. The use of HST images as input for weak-lensing image simulations

Data from the space telescope will enable cosmic shear measurements to be carried out with very small statistical errors, necessitating a corresponding level of systematic error control. A common approach to correct for shear biases involves calibrating shape measurement methods using image simulations with known input shear. Given their high resolution, galaxies observed with the (HST) can, in principle, be utilised to emulate observations of sheared galaxy images with realistic morphologies. In this work, we employ a GalSim -based testing environment to investigate whether uncertainties in the HST point spread function (PSF) model or in data processing techniques introduce significant biases in weak-lensing (WL) shear calibration. We used single S'ersic galaxy models to simulate both HST and observations. We then ‘Euclidised’ our HST simulations and compared the results with the directly simulated images. For this comparison, we utilised a moment-based shape measurement algorithm and galaxy model fits. Through the Euclidisation procedure, we effectively reduced the residual multiplicative biases in shear measurements to sub-percent levels. This achievement was made possible by employing either the native pixel scales of the instruments, utilising the Lanczos15 interpolation kernel, correcting for noise correlations, and ensuring consistent galaxy signal-to-noise ratios between simulation branches. Alternatively, a finer pixel scale can be employed alongside deeper HST data. However, the Euclidisation procedure requires further analysis on the impact of the correlated noise, to estimate calibration bias. We found that additive biases can be mitigated by applying a post-deconvolution isotropisation in the Euclidisation set-up. Additionally, we conducted an in-depth analysis of the accuracy of TinyTim HST PSF models using star fields observed in the F606W and F814W filters. We observe that F606W images exhibit a broader scatter in the recovered best-fit focus, compared to those in the F814W filter. Estimating the focus value for the F606W filter in lower stellar density regimes has allowed us to reveal significant statistical uncertainties.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2025-01-10
DOI
https://doi.org/10.1051/0004-6361/202451587
Citations
1
Primary Topic
Advanced X-ray Imaging Techniques
Type
article
Field-Weighted Citation Impact
1.88

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article

Euclid preparation. LX. The use of HST images as input for weak-lensing image simulations

O. Marggraf, M. Tewes, T. Schrabback, R. Massey et al.
1 citations
Astronomy and Astrophysics
Advanced X-ray Imaging Techniques
1.88
article

Euclid preparation. LX. The use of HST images as input for weak-lensing image simulations

O. Marggraf, M. Tewes, T. Schrabback, R. Massey, Henk Hoekstra, B. Gillis, A. Hornstrup, T. Kitching, Diana Scognamiglio, Alex Robertson, C. S. Carvalho, I. Tereno, E. M. Huff
article en
1 citations

Abstract

Data from the space telescope will enable cosmic shear measurements to be carried out with very small statistical errors, necessitating a corresponding level of systematic error control. A common approach to correct for shear biases involves calibrating shape measurement methods using image simulations with known input shear. Given their high resolution, galaxies observed with the (HST) can, in principle, be utilised to emulate observations of sheared galaxy images with realistic morphologies. In this work, we employ a GalSim -based testing environment to investigate whether uncertainties in the HST point spread function (PSF) model or in data processing techniques introduce significant biases in weak-lensing (WL) shear calibration. We used single S'ersic galaxy models to simulate both HST and observations. We then ‘Euclidised’ our HST simulations and compared the results with the directly simulated images. For this comparison, we utilised a moment-based shape measurement algorithm and galaxy model fits. Through the Euclidisation procedure, we effectively reduced the residual multiplicative biases in shear measurements to sub-percent levels. This achievement was made possible by employing either the native pixel scales of the instruments, utilising the Lanczos15 interpolation kernel, correcting for noise correlations, and ensuring consistent galaxy signal-to-noise ratios between simulation branches. Alternatively, a finer pixel scale can be employed alongside deeper HST data. However, the Euclidisation procedure requires further analysis on the impact of the correlated noise, to estimate calibration bias. We found that additive biases can be mitigated by applying a post-deconvolution isotropisation in the Euclidisation set-up. Additionally, we conducted an in-depth analysis of the accuracy of TinyTim HST PSF models using star fields observed in the F606W and F814W filters. We observe that F606W images exhibit a broader scatter in the recovered best-fit focus, compared to those in the F814W filter. Estimating the focus value for the F606W filter in lower stellar density regimes has allowed us to reveal significant statistical uncertainties.

Astronomy and Astrophysics
Université Claude Bernard Lyon 1 (FR), Institut polytechnique de Grenoble (FR), University of Geneva (CH), Leiden University (NL), California Institute of Technology (US), Uppsala University (SE), University of Copenhagen (DK), Centre National de la Recherche Scientifique (FR), University of Minnesota (US), Institute of Space Sciences (ES), University of Hawaii System (US), Jet Propulsion Laboratory (US), University of Helsinki (FI), Université Toulouse III - Paul Sabatier (FR), Consejo Superior de Investigaciones Científicas (ES), University of Bonn (DE), Scuola Internazionale Superiore di Studi Avanzati (IT), University of Padua (IT), University of Lisbon (PT), University of Trieste (IT), University of Turku (FI), Universidad de La Laguna (ES), Stockholm University (SE), Queen Mary University of London (GB), Kavli Institute for the Physics and Mathematics of the Universe (JP), University of Groningen (NL), Université Fédérale de Toulouse Midi-Pyrénées (FR), Universidade do Porto (PT), Royal Holloway University of London (GB), Saint Joseph University (LB), University of Oslo (NO), Institute for High Energy Physics (ES), University of Milan (IT), Durham University (GB), Universität Innsbruck (AT), Princeton University (US), University of Ferrara (IT), Université Côte d'Azur (FR), University of Zurich (CH), The Open University (GB), University of California, Irvine (US), Aarhus University (DK), Université Paris Cité (FR), Aix-Marseille Université (FR), Heidelberg University (DE), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris Sciences et Lettres (FR), Université Paris-Saclay (FR), Centre National d'Études Spatiales (FR), Arcetri Astrophysical Observatory (IT), Helsinki Institute of Physics (FI), Astronomical Observatory of Rome (IT), Agenzia Spaziale Italiana (IT), Trieste Astronomical Observatory (IT), Institut d'Astrophysique de Paris (FR), Astronomical Observatory of Capodimonte (IT), Laboratoire AstroParticule et Cosmologie (FR), Brera Astronomical Observatory (IT), University of Surrey (GB), University of Manchester (GB), Institute for High Performance Computing and Networking (IT), Universidad Politécnica de Cartagena (ES), Sorbonne Université (FR), University of Oxford (GB), Técnicas Reunidas (Spain) (ES), Astrophysique, Instrumentation et Modélisation (FR), Laboratoire Univers et Théories (FR), Institute of Astrophysics and Space Sciences (PT), ARC Centre of Excellence for Dark Matter Particle Physics (AU), Max Planck Institute for Extraterrestrial Physics (DE), Institut d'Estudis Espacials de Catalunya (ES), European Space Astronomy Centre (ES), Istituto Nazionale di Fisica Nucleare, Sezione di Torino (IT), Institute for Space Astrophysics and Planetology (IT), Institut d'Astrophysique Spatiale (FR), Istituto Nazionale di Fisica Nucleare, Sezione di Padova (IT), Osservatorio Astrofisico di Torino (IT), Royal Observatory (GB), Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Napoli (IT), Centro de Astrofísica da Universidade do Porto (PT), Max Planck Institute for Astronomy (DE), Istituto di Radioastronomia di Bologna (IT), Federico II University Hospital (IT), Université Bourgogne Franche-Comté (FR), Istituto Nazionale di Fisica Nucleare, Sezione di Genova (IT), Observatoire de la Côte d’Azur (FR), CEA Paris-Saclay (FR), Instituto de Astrofísica de Canarias (ES), Institut National de Physique Nucléaire et de Physique des Particules (FR), Institute of Space Science - INFLPR Subsidiary (RO), Centre de Calcul de l’Institut National de Physique Nucléaire et de Physique des Particules (FR), Osservatorio Astronomico della Regione Autonoma Valle d'Aosta (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Bologna (IT), Port d'Informació Científica (ES), Istituto Nazionale di Fisica Nucleare, Sezione di Trieste (IT), Institute for Fundamental Physics of the Universe (IT), Damien Foundation (BD), Flatiron Health (United States) (US), Istituto Nazionale di Fisica Nucleare, Sezione di Roma I (IT), Osservatorio Astronomico di Padova (IT), European Space Research Institute (IT), Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (ES), Institut de Recherche en Astrophysique et Planétologie (FR), Infrared Processing and Analysis Center (US), Osservatorio di Astrofisica e Scienza dello Spazio, Fondazione ICSC Centro Nazionale di Ricerca in High Performance Computing, Big Data e Quantum Computing, Flatiron Institute (US), European Space Research and Technology Centre (NL), University College London (GB), Imperial College London (GB), École Polytechnique Fédérale de Lausanne (CH), University of Turin (IT), Swinburne University of Technology (AU), New York University (US), Case Western Reserve University (US), University of Portsmouth (GB), Universidad Autónoma de Madrid (ES), Saint Mary's University (CA), University of Chile (CL), Heidelberg Institute for Theoretical Studies (DE), The University of Tokyo (JP), Ludwig-Maximilians-Universität München (DE), University of Genoa (IT), Sapienza University of Rome (IT), University of the Western Cape (ZA), National Institute for Astrophysics (IT), RWTH Aachen University (DE), Université Grenoble Alpes (FR), Ruhr University Bochum (DE), Netherlands Institute for Radio Astronomy (NL), University of Bologna (IT), Universitat Politècnica de Catalunya (ES), Technical University of Denmark (DK), University of Edinburgh (GB), Aalto University (FI)
National Aeronautics and Space Administration
Openalex Percentile: Top 22%
Advanced X-ray Imaging Techniques
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