How accurately can we measure weak gravitational shear

By T. Erben, L. Waerbeke, E. Bertin, Y. Mellier, P. Schneider. 2000

171 citations recorded by the source corpus.

With the recent detection of cosmic shear, the most challenging effect of weak gravitational lensing has been observed. The main difficulties for this detection were the need for a large amount of high quality data and the control of systematics during the gravitational shear measurement process, in particular those coming from the Point Spread Function anisotropy. In this paper we perform detailed simulations with the state-of-the-art algorithm developed by Kaiser, Squires and Broadhurst (KSB) to measure gravitational shear. We show that for realistic PSF profiles the KSB algorithm can recover any shear amplitude in the range $0.012 < |\gammavec |<0.32$ with a relative, systematic error of $10-15%$. We give quantitative limits on the PSF correction method as a function of shear strength, object size, signal-to-noise and PSF anisotropy amplitude, and we provide an automatic procedure to get a reliable object catalog for shear measurements out of the raw images.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/b8c7c537fb0fcef58f878dd1b4ed6e64bb1b71e2

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

The Shear Testing Programme – I. Weak lensing analysis of simulated ground-based observations (2005, methodology): “Centroid accuracy is however likely to be data dependent, and S/N dependent (see Erben et al. 2001).”
First Cosmic Shear Results from the Canada-France-Hawaii Telescope Wide Synoptic Legacy Survey (2005, methodology): “This particular method has been tested in great detail (e.g., Hoekstra et al. 1998, 2002c; Bacon et al. 2001; Erben et al. 2001; Heymans et al. 2005) and is widely used for cosmic shear studies.”
Evidence of the accelerated expansion of the Universe from weak lensing tomography with COSMOS (2009, methodology): “Summary of our KSB+ implementation We measure galaxy shapes using the Erben et al. (2001) implementation of the KSB+ formalism (Kaiser et al. 1995; Luppino & Kaiser 1997; Hoekstra et al. 1998), as done in the earlier ACS weak lensing analysis of Schrabback et al. (2007).”
Detection of large-scale intrinsic ellipticity—density correlation from the Sloan Digital Sky Survey and implications for weak lensing surveys (2005, background): “The list is long, and much of the effort by the weak lensing observers in the past several years has been devoted to these issues (Kaiser 2000; Erben et al. 2001; Bernstein & Jarvis 2002; Hirata & Seljak 2003a; Vale et al. 2004; Van Waerbeke et al. 2005).”
Combining Lens Distortion and Depletion to Map the Mass Distribution of A1689 (2007, methodology): “We have modified the method somewhat following the procedures described in Erben et al. (2001).”
THE DENSITY PROFILES OF MASSIVE, RELAXED GALAXY CLUSTERS. I. THE TOTAL DENSITY OVER THREE DECADES IN RADIUS (2012, methodology): “…resolved, well detected galaxies for our shear analysis via the following criteria: (1) S/N > 7, where S/N is the detection significance defined in Erben et al. (2001) measured with a window function having σ = rh; (2) 1.15rh∗ < rh < 6 pixels, where r∗h is the median stellar FLUX RADIUS, to avoid…”
CFHTLenS: the Canada–France–Hawaii Telescope Lensing Survey – imaging data and catalogue products (2012, background): “S = 2 corresponds to a signal-to-noise ratio of νSN ∼ 7 (Erben et al. 2001).”
The Shear TEsting Programme 2: Factors affecting high precision weak lensing analyses (2006, methodology): “Bacon et al. (2001), Erben et al. (2001) and Hoekstra et al. (2002) ran their shear-measurement methods on such images.”
Weighing the Giants - I. Weak-lensing masses for 51 massive galaxy clusters: project overview, data analysis methods and cluster images (2012, methodology): “Since the trace-free part of the Pg tensor is much smaller than the trace, we follow Erben et al. (2001) and make the approximations (P?sm)−1P?sh → Tr[P ?sh] Tr[P?sm] =: T?”
DEEP U BAND AND R IMAGING OF GOODS-SOUTH: OBSERVATIONS, DATA REDUCTION AND FIRST RESULTS, (2009, methodology): “For the completeness and detection limit analysis, we used Skymaker (Erben et al. 2001) to generate images of artificial objects and add them to the UV -band mosaic image.”
Shapelets — II. A method for weak lensing measurements (2001, background): “Firstly, it is not sufficiently accurate or unbiased to measure shears of a fraction of 1% (cf Bacon et al 2001a, Erben et al 2001).”
Creation of cosmic structure in the complex galaxy cluster merger Abell 2744 (2011, methodology): “We measure galaxy shapes and perform PSF correction using the IMCAT package (provided by Kaiser et al. 1995) in the same pipeline as Okabe et al. (2010,a) with some modifications following Erben et al. (2001).”
Shapes and Shears, Stars and Smears: Optimal Measurements for Weak Lensing (2001, methodology): “…our geometric transformation relations, so the mean polarizability of galaxies must be calculated in some parameter space, e.g. of flux, size, and e. Binning or smoothing in some such space is common to most of the KSB-based weighting schemes as well (Erben et al. 2001; Hoekstra et al. 2000).”
LoCuSS: Subaru Weak Lensing Study of 30 Galaxy Clusters (2009, methodology): “First the tensor P g˛ˇ for each galaxy is estimated based on a scalar correction approximation (Hudson et al. 1998; Hoekstra et al. 1998; Erben et al. 2001) as .”
Galaxy–galaxy weak lensing in the Sloan Digital Sky Survey: intrinsic alignments and shear calibration errors (2004, methodology): “This effect has not been previously analysed, although it is present implicitly in simulations (e.g. Bacon et al. 2001; Erben et al. 2001).”
The Intrinsic Alignment of Galaxies and its Impact on Weak Gravitational Lensing in an Era of Precision Cosmology (2014, methodology): “…and planned weak lensing surveys (see for example, Croft and Metzler (2000); Heavens et al. (2000); Bacon et al. (2001); Catelan et al. (2001); Erben et al. (2001); Bernstein and Jarvis (2002); Brown et al. (2002); King and Schneider (2002); Hirata and Seljak (2003); Refregier (2003b); van…”
Gravitational lensing (2010, methodology): “The authors of [114] used numerical simulations to show that relative accuracies of 10% .”
Weak Gravitational Lensing with COSMOS: Galaxy Selection and Shape Measurements (2007, result): “…shear on COSMOS-like images, the RRG method requires an overall calibration factor of C ¼ (0:86þ0:07 0:05) 1, so that ̃ ¼ C " G : ð14Þ The necessity for such calibration factors has long been known in the field (e.g., Bacon et al. 2001; Erben et al. 2001), and is in accord with results from STEP1.”