Bayesian galaxy shape measurement for weak lensing surveys – III. Application to the Canada–France–Hawaii Telescope Lensing Survey

By L. Miller, Catherine Heymans, Thomas D. Kitching, L. Waerbeke, T. Erben, H. Hildebrandt, H. Hoekstra, Y. Mellier, B. Rowe, Jean Coupon and 10 more. 2012

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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 ν_(SN) ≳ 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.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Computer Vision and Pattern Recognition

View Paper: https://www.semanticscholar.org/paper/9510aab1f37e443018f3c564f317775665bdb8d3

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Citations in the corpus

CFHTLenS revisited: assessing concordance with Planck including astrophysical systematics (2016, methodology): “We applied additive shear calibration corrections to the measured ellipticities and multiplicative shear calibration corrections to the cosmic shear measurements (following Heymans et al. 2012 and Miller et al. 2013).”
The first and second data releases of the Kilo-Degree Survey (2015, methodology): “…applications (Sifón et al. 2015; Viola et al. 2015; van Uitert et al. 2015) of KiDS data rely on the KiDS-ESO-DR1 and -DR2 data products presented here for photometric redshifts, while galaxy shape measurements are based on a dedicated pipeline (see Erben et al. 2013; Miller et al. 2013).”
Gravitational lensing analysis of the Kilo-Degree Survey (2015, methodology): “…was performed only on the r-band data, with image calibration and processing using the THELI pipeline (Erben et al. 2013, henceforth E+13; Schirmer 2013), and object detection and classification, PSF modelling and shape measurements using the lensfit code (Miller et al. 2013, henceforth M+13).”
KiDS+GAMA : cosmology constraints from a joint analysis of cosmic shear, galaxy-galaxy lensing, and angular clustering (2017, methodology): “…t and × the tangential and cross-component of the ellipticities of galaxies i and j, measured with respect to their separation vector, and w the inverse variance weight of the shape measurements, which comes from our shape measurement method lensfit (Miller et al. 2013; Fenech Conti et al. 2017).”
KiDS-450 + 2dFLenS: Cosmological parameter constraints from weak gravitational lensing tomography and overlapping redshift-space galaxy clustering (2017, methodology): “While THELI (Erben et al. 2013) and ASTRO-WISE (Begeman et al. 2013; de Jong et al. 2015) were used to process the raw pixel data, the shears were measured using lensfit (Miller et al. 2013) and calibrated using a dedicated large suite of image simulations (Fenech-Conti et al. 2017).”
Lensing is Low: Cosmology, Galaxy Formation, or New Physics? (2016, methodology): “…the weak-lensing signal of CMASS galaxies, we use a combination of two data sets: the Canada–France–Hawaii Telescope Lensing Survey (CFHTLenS; Heymans et al. 2012; Miller et al. 2013) and the Canada–France–Hawaii Telescope Stripe 82 2 Also see http://www.sdss3.org/dr9/tutorials/lss_galaxy.php.”
KiDS+VIKING-450: Cosmic shear tomography with optical and infrared data (2018, methodology): “Shape measurements with lensfit The shapes of galaxies, described by the two ellipticity components 1 and 2, were measured from THELI-reduced individual r-band exposures with the self-calibrating version of the lensfit algorithm (Miller et al. 2007, 2013).”
Weak Gravitational Lensing (2012, methodology): “Following a similar approach, the lensfit method (Miller et al., 2007; Kitching et al., 2008) measures the shear by fitting realistic galaxy profiles in a fully Bayesian way.”
Observational probes of cosmic acceleration (2012, background): “After a thorough analysis, the lensing results and cosmological implications were recently published (Heymans et al., 2012b; Benjamin et al., 2012; Erben et al., 2012; Kilbinger et al., 2012; Miller et al., 2013).”
KiDS-450: cosmological parameter constraints from tomographic weak gravitational lensing (2016, methodology): “The bulge-to-total flux ratio, the fraction of bulge-dominated galaxies and the galaxy ellipticity distribution are matched to the lensFIT prior (Miller et al. 2013).”
KiDS-450: The tomographic weak lensing power spectrum and constraints on cosmological parameters (2017, methodology): “The galaxy shapes are measured from the THELI-processed data with the shape measurement software lensfit (Miller et al. 2013; Fenech Conti et al. 2017).”
The Hyper Suprime-Cam Software Pipeline (2017, methodology): “…systematic errors, however, and recent surveys focused on weak lensing have avoided these problems by instead using models fit simultaneously to images from all epochs for their most sensitive measurements (CFHTLens, Miller et al. 2013; DES, Jarvis et al. 2016; and KiDS, Kuijken et al. 2015).”
Cosmic Discordance: Are Planck CMB and CFHTLenS weak lensing measurements out of tune? (2014, methodology): “The multiplicative bias in the CFHTLenS shape measurements was calibrated using image simulations (Miller et al. 2013) and the average value of (1 + m) was found to be 0.94.”
KiDS-450: testing extensions to the standard cosmological model (2016, methodology): “…lensing observations by the Canada–France–Hawaii Telescope Lensing Survey (CFHTLenS; Heymans et al. 2012; Hildebrandt et al. 2012; Erben et al. 2013; Miller et al. 2013) were also found to exhibit a similar tension with Planck (e.g. Planck Collaboration XVI 2014; MacCrann et al. 2015; Köhlinger…”