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Title: GREAT3 results - I. Systematic errors in shear estimation and the impact of real galaxy morphology

The study present first results from the third GRavitational lEnsing Accuracy Testing (GREAT3) challenge, the third in a sequence of challenges for testing methods of inferring weak gravitational lensing shear distortions from simulated galaxy images. GREAT3 was divided into experiments to test three specific questions, and included simulated space- and ground-based data with constant or cosmologically varying shear fields. The simplest (control) experiment included parametric galaxies with a realistic distribution of signal-to-noise, size, and ellipticity, and a complex point spread function (PSF). The other experiments tested the additional impact of realistic galaxy morphology, multiple exposure imaging, and the uncertainty about a spatially varying PSF; the last two questions will be explored in Paper II. The 24 participating teams competed to estimate lensing shears to within systematic error tolerances for upcoming Stage-IV dark energy surveys, making 1525 submissions overall. GREAT3 saw considerable variety and innovation in the types of methods applied. Several teams now meet or exceed the targets in many of the tests conducted (to within the statistical errors). We conclude that the presence of realistic galaxy morphology in simulations changes shear calibration biases by ~1 per cent for a wide range of methods. Other effects such as truncation biasesmore » due to finite galaxy postage stamps, and the impact of galaxy type as measured by the Sérsic index, are quantified for the first time. Our results generalize previous studies regarding sensitivities to galaxy size and signal-to-noise, and to PSF properties such as seeing and defocus. Almost all methods’ results support the simple model in which additive shear biases depend linearly on PSF ellipticity.« less
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  1. Carnegie Mellon Univ., Pittsburgh, PA (United States)
  2. Univ. College London, London (United Kingdom)
  3. Princeton Univ., Princeton, NJ (United States)
  4. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  5. Univ. Pierre et Marie Curie, Paris (France)
  6. SLAC National Accelerator Lab., Menlo Park, CA (United States); Centre de Calcul de l'IN2P3 (France)
  7. Ecole Polytechnique Federale de Lausanne (EPFL), Versoix (Switzerland)
  8. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  9. Univ. of Malta (Malta)
  10. New York Univ., New York, NY (United States)
  11. The Ohio State Univ., Columbus, OH (United States)
  12. Univ. of California, Davis, CA (United States)
  13. Univ. College London, London (United Kingdom); Institut fur Astronomie, Zurich (Switzerland)
  14. Service d'Astrophysique, Cedex (France)
  15. Shanghai Astronomibal Observatory, Shanghai (China)
  16. Univ. of Pennsylvania, Philadelphia, PA (United States)
  17. Stanford Univ., Stanford, CA (United States)
  18. Univ. of Oxford, Oxford (United Kingdom)
  19. Princeton Univ., Princeton, NJ (United States); Univ. of Tokyo, Chiba (Japan)
  20. Argelander-Institut fur Astronomie, Bonn (Germany)
  21. National Astronomical Observatory of Japan, Tokyo (Japan)
  22. California Institute of Technology, Pasadena, CA (United States)
  23. Brookhaven National Lab. (BNL), Upton, NY (United States)
  24. Univ. of Malta (Malta); Univ. of Oxford, Oxford (United Kingdom)
  25. Shanghai Jiao Tong Univ., Shanghai (China)
  26. Univ. of Manchester (United Kingdom)
Publication Date:
Report Number(s):
Journal ID: ISSN 0035-8711; KA2301020
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 450; Journal Issue: 3; Journal ID: ISSN 0035-8711
Royal Astronomical Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; gravitational lensing; weak - methods; data analysis - techniques; image processing - cosmology; observations
OSTI Identifier: