期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 429, 期 4, 页码 2858-2880出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/sts454
关键词
gravitational lensing: weak; methods: data analysis; methods: statistical; cosmology: observations
资金
- Canadian Space Agency
- European Research Council under the EC [240185]
- Royal Society
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- Canadian Institute for Advanced Research (CIfAR, Cosmology and Gravity program)
- Deutsche Forschungsgemeinschaft [ER 327/3-1]
- Transregional Collaborative Research Centre [TR 33 - 'The Dark Universe']
- Marie Curie IOF [252760]
- CITA
- Marie Curie IRG grant [230924]
- Netherlands Organization for Scientific Research (NWO) [639.042.814]
- European Research Council under the EC FP7 grant [279396]
- CNRS/INSU (Institut National des Sciences de l'Univers)
- Programme National Galaxies et Cosmologie (PNCG)
- NSF [AST 0807304, AST-0444059-001]
- NSFC [11103012, 10878003]
- Innovation Program [12ZZ134]
- Chen Guang project of SMEC [10CG46]
- STCSM [11290706600]
- Pujiang Program [12PJ1406700]
- SAO [GO0-11147A]
- NWO
- Netherlands Organization for Scientific Research (NWO)
- Beecroft Institute for Particle Astrophysics and Cosmology
- Canada Foundation for Innovation under Compute Canada
- Government of Ontario
- Ontario Research Fund - Research Excellence
- University of Toronto
- STFC [ST/H002456/1, ST/J001422/1] Funding Source: UKRI
- Science and Technology Facilities Council [ST/H002456/1, ST/J001422/1] Funding Source: researchfish
- European Research Council (ERC) [240185] Funding Source: European Research Council (ERC)
A likelihood-based method for measuring weak gravitational lensing shear in deep galaxy surveys is described and applied to the Canada-France-Hawaii Telescope (CFHT) Lensing Survey (CFHTLenS). CFHTLenS comprises 154 deg(2) of multi-colour optical data from the CFHT Legacy Survey, with lensing measurements being made in the i' band to a depth i(AB)' < 24.7, for galaxies with signal-to-noise ratio nu(SN) greater than or similar to 10. The method is based on the lensfit algorithm described in earlier papers, but here we describe a full analysis pipeline that takes into account the properties of real surveys. The method creates pixel-based models of the varying point spread function (PSF) in individual image exposures. It fits PSF-convolved two-component (disc plus bulge) models to measure the ellipticity of each galaxy, with Bayesian marginalization over model nuisance parameters of galaxy position, size, brightness and bulge fraction. The method allows optimal joint measurement of multiple, dithered image exposures, taking into account imaging distortion and the alignment of the multiple measurements. We discuss the effects of noise bias on the likelihood distribution of galaxy ellipticity. Two sets of image simulations that mirror the observed properties of CFHTLenS have been created to establish the method's accuracy and to derive an empirical correction for the effects of noise bias.
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