TY - JOUR
T1 - GREAT3 results - I. Systematic errors in shear estimation and the impact of real galaxy morphology
AU - Mandelbaum, Rachel
AU - Rowe, Barnaby
AU - Armstrong, Robert
AU - Bard, Deborah
AU - Bertin, Emmanuel
AU - Bosch, James
AU - Boutigny, Dominique
AU - Courbin, Frederic
AU - Dawson, William A.
AU - Donnarumma, Annamaria
AU - Conti, Ian Fenech
AU - Gavazzi, Raphaël
AU - Gentile, Marc
AU - Gill, Mandeep S.S.
AU - Hogg, David W.
AU - Huff, Eric M.
AU - James Jee, M.
AU - Kacprzak, Tomasz
AU - Kilbinger, Martin
AU - Kuntzer, Thibault
AU - Lang, Dustin
AU - Luo, Wentao
AU - March, Marisa C.
AU - Marshall, Philip J.
AU - Meyers, Joshua E.
AU - Miller, Lance
AU - Miyatake, Hironao
AU - Nakajima, Reiko
AU - Mboula, Fred Maurice Ngolé
AU - Nurbaeva, Guldariya
AU - Okura, Yuki
AU - Paulin-Henriksson, Stéphane
AU - Rhodes, Jason
AU - Schneider, Michael D.
AU - Shan, Huanyuan
AU - Sheldon, Erin S.
AU - Simet, Melanie
AU - Starck, Jean Luc
AU - Sureau, Florent
AU - Tewes, Malte
AU - Adami, Kristian Zarb
AU - Zhang, Jun
AU - Zuntz, Joe
N1 - Publisher Copyright:
© 2015 The Authors.
PY - 2015/7/1
Y1 - 2015/7/1
N2 - 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 ~1 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 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.
AB - 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 ~1 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 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.
KW - Cosmology: observations
KW - Gravitational lensing: weak
KW - Methods: data analysis
KW - Techniques: image processing
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U2 - 10.1093/mnras/stv781
DO - 10.1093/mnras/stv781
M3 - Article
AN - SCOPUS:84930853018
SN - 0035-8711
VL - 450
SP - 2963
EP - 3007
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -