The Shear TEsting Programme 2: Factors affecting high precision weak lensing analyses

By Richard J. Massey, Catherine Heymans, J. Bergé, G. Bernstein, Sarah Bridle, D. Clowe, H. Dahle, Richard S. Ellis, T. Erben, M. Hetterscheidt and 21 more. 2006

312 citations recorded by the source corpus.

The Shear Testing Programme (STEP) is a collaborative project to improve the accuracy and reliability of weak-lensing measurement, in preparation for the next generation of wide-field surveys. We review 16 current and emerging shear-measurement methods in a common language, and assess their performance by running them (blindly) on simulated images that contain a known shear signal. We determine the common features of algorithms that most successfully recover the input parameters. A desirable goal would be the combination of their best elements into one ultimate shear-measurement method. In this analysis, we achieve previously unattained discriminatory precision via a combination of more extensive simulations and pairs of galaxy images that have been rotated with respect to each other. That removes the otherwise overwhelming noise from their intrinsic ellipticities. Finally, the robustness of our simulation approach is confirmed by testing the relative calibration of methods on real data. Weak-lensing measurements have improved since the first STEP paper. Several methods now consistently achieve better than 2 per cent precision, and are still being developed. However, we can now distinguish all methods from perfect performance. Our main concern continues to be the potential for a multiplicative shear calibration bias: not least because this cannot be internally calibrated with real data. We determine which galaxy populations are responsible for bias and, by adjusting the simulated observing conditions, we also investigate the effects of instrumental and atmospheric parameters. The simulated point spread functions are not allowed to vary spatially, to avoid additional confusion from interpolation errors. We have isolated several previously unrecognized aspects of galaxy shape measurement, in which focused development could provide further progress towards the sub-per cent level of precision desired for future surveys. These areas include the suitable treatment of image pixellization and galaxy morphology evolution. Ignoring the former effect affects the measurement of shear in different directions, leading to an overall underestimation of shear and hence the amplitude of the matter power spectrum. Ignoring the second effect could affect the calibration of shear estimators as a function of galaxy redshift, and the evolution of the lensing signal, which will be vital to measure parameters including the dark energy equation of state.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/353c6c201eba626ed72e4e5acb810e507b57d9dc

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Citations in the corpus

Dark Energy Survey Year 1 results: weak lensing shape catalogues (2017, background): “…several such exercises, most notably the Shear Testing Programme and GRavitational lEnsing Accuracy Testing (GREAT) challenges (Heymans et al. 2006; Massey et al. 2007; Bridle et al. 2010; Kitching et al. 2012; Mandelbaum et al. 2015), which have illuminated many of the issues that the field must…”
The first-year shear catalog of the Subaru Hyper Suprime-Cam Subaru Strategic Program Survey (2017, methodology): “More generally, any method based on the use of second moments to estimate shears cannot be completely independent of the details of the galaxy light profiles, such as the overall galaxy morphology and presence of detailed substructure (Massey et al. 2007a; Bernstein 2010; Zhang & Komatsu 2011).”
A WEAK LENSING STUDY OF X-RAY GROUPS IN THE COSMOS SURVEY: FORM AND EVOLUTION OF THE MASS–LUMINOSITY RELATION (2009, unknown): “…et al. 2000; Hasinger et al. 2001; Finoguenov et al. 2007; Vikhlinin et al. 2008), d) spectroscopic identification (e.g. Gerke et al. 2005; Miller et al. 2005; Knobel et al. 2009), and e) detection via weak lensing maps (e.g. Marian & Bernstein 2006; Miyazaki et al. 2007; Massey et al. 2007).”
Masses of Galaxy Clusters from Gravitational Lensing (2013, background): “An overview of a number of these can be found in Heymans et al. (2006), Massey et al. (2007), Bridle et al. (2010) and Kitching et al. (2012).”
Cosmological constraints from the 100-deg2 weak-lensing survey (2007, methodology): “With the recent first measurements of a changing lensing signal as a function of redshift (Bacon et al. 2005; Wittman 2005; Semboloni et al. 2006; Massey et al. 2007b), and the first weak-lensing constraints on dark energy (Hoekstra et al. 2006; Jarvis et al. 2006; Kitching et al. 2007; Schimd et…”
Constraints on intrinsic alignment contamination of weak lensing surveys using the MegaZ-LRG sample (2010, background): “…amplitudeA from the combined samples, there could also be some effect that is a function of galaxy properties (typically apparent size andS/N, see Massey et al. 2007a), which would manifest as a difference between the SDSS Main samples (very bright apparent magnitudes and wellresolved), the…”
COSMOS: Three-dimensional Weak Lensing and the Growth of Structure (2007, methodology): “As described in Leauthaud et al. (2007), we have tested our pipeline on simulated images created with the same Massey et al. (2004a) package used for STEP, but tailored specifically to the image characteristics of the COSMOS data.”
Evidence of the accelerated expansion of the Universe from weak lensing tomography with COSMOS (2009, methodology): “Note that the analysis of Massey et al. (2007c) yields tighter statistical errors, which may be a result of their covariance estimate from the variation between the four COSMOS quadrants.”
Gravitational lensing (2010, methodology): “The shear testing programme (STEP, [186, 311]) was launched to test and improve the accuracy of shear measurements from weakly distorted images of distant galaxies in the presence of several perturbing effects.”
The Sloan Lens ACS Survey. IV. The Mass Density Profile of Early-Type Galaxies out to 100 Effective Radii (2007, methodology): “Our implementation of KSB builds on the proposed improvements suggested by the STEP1 and STEP2 results (Heymans et al. 2006b; Massey et al. 2007).”
CFHTLenS: the Canada–France–Hawaii Telescope Lensing Survey – imaging data and catalogue products (2012, methodology): “It is interesting to note that the only shape measurement challenge to simulate the relatively strong 10%-level PSF distortions that are typical in CFHT MegaCam imaging found significant errors for KSB+ in this regime (Massey et al. 2007a).”
Weighing the Giants - I. Weak-lensing masses for 51 massive galaxy clusters: project overview, data analysis methods and cluster images (2012, methodology): “We choose the KSB method because it has been extensively tested (Heymans et al. 2006; Massey et al. 2007) and, despite its simplicity, performs robustly on a variety of data.”
CLASH: JOINT ANALYSIS OF STRONG-LENSING, WEAK-LENSING SHEAR, AND MAGNIFICATION DATA FOR 20 GALAXY CLUSTERS (2015, methodology): “The shear analysis pipeline of Umetsu et al. (2014) was implemented based on the procedures described in Umetsu et al. (2010) and on verification tests with mock ground-based observations (Massey et al. 2007; Oguri et al. 2012).”
LoCuSS: Subaru Weak Lensing Study of 30 Galaxy Clusters (2009, background): “As studied in detail by the STEP project (Massey et al. 2007; Heymans et al. 2006), the various shape measurement methods developed to date differ in galaxy ellipticity measurements by up to a multiplicative bias of 10%.”
Very weak lensing in the CFHTLS Wide: Cosmology from cosmic shear in the linear regime (2007, methodology): “As described in Heymans et al. (2006a) and Massey et al. (2007b), the shear bias parameter m often depends on object sizes, rg, and magnitudes mag.”