GREAT3 results I: systematic errors in shear estimation and the impact of real galaxy morphology
Abstract
We 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 per cent for a wide range of methods. Other effects such as truncation biases due to finite galaxy postage stamps, and the impact of galaxy type as measured by the S\'{e}rsic 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.
Keywords
Cite
@article{arxiv.1412.1825,
title = {GREAT3 results I: systematic errors in shear estimation and the impact of real galaxy morphology},
author = {Rachel Mandelbaum and Barnaby Rowe and Robert Armstrong and Deborah Bard and Emmanuel Bertin and James Bosch and Dominique Boutigny and Frederic Courbin and William A. Dawson and Annamaria Donnarumma and Ian Fenech Conti and Raphael Gavazzi and Marc Gentile and Mandeep S. S. Gill and David W. Hogg and Eric M. Huff and M. James Jee and Tomasz Kacprzak and Martin Kilbinger and Thibault Kuntzer and Dustin Lang and Wentao Luo and Marisa C. March and Philip J. Marshall and Joshua E. Meyers and Lance Miller and Hironao Miyatake and Reiko Nakajima and Fred Maurice Ngole Mboula and Guldariya Nurbaeva and Yuki Okura and Stephane Paulin-Henriksson and Jason Rhodes and Michael D. Schneider and Huanyuan Shan and Erin S. Sheldon and Melanie Simet and Jean-Luc Starck and Florent Sureau and Malte Tewes and Kristian Zarb Adami and Jun Zhang and Joe Zuntz},
journal= {arXiv preprint arXiv:1412.1825},
year = {2023}
}
Comments
32 pages + 15 pages of technical appendices; 28 figures; published in MNRAS; all data and other information may be found at https://github.com/barnabytprowe/great3-public as the GREAT3 website and leaderboard are no longer live. v3 has updates to this comment only