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Weak gravitational lensing requires precise measurements of galaxy shapes and therefore an accurate knowledge of the PSF model. The latter can be a source of systematics that affect the shear two-point correlation function. A key stake of…

Weak gravitational lensing is one of the key probes of cosmology. Cosmic shear surveys aimed at measuring the distribution of matter in the universe are currently being carried out (Pan-STARRS) or planned for the coming decade (DES, LSST,…

Cosmology and Nongalactic Astrophysics · Physics 2013-11-22 Alberto Vallinotto

Weak gravitational lensing provides a direct way to study the mass distribution of clusters of galaxies at large radii. Unfortunately, large scale structure along the line of sight also contributes to the lensing signal, and consequently…

Astrophysics · Physics 2009-11-07 Henk Hoekstra

This chapter provides a comprehensive overview of weak gravitational lensing and its current applications in cosmology. We begin by introducing the fundamental concepts of gravitational lensing and derive the key equations for the…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-06 J. Prat , D. Bacon

Kaiser & Squires have proposed a technique for mapping the dark matter in galaxy clusters using the coherent weak distortion of background galaxy images caused by gravitational lensing. We investigate the effectiveness of this technique…

Astrophysics · Physics 2015-06-24 Gillian Wilson , Shaun Cole , Carlos S. Frenk

Dedicated 'Stage IV' observatories will soon observe the entire extragalactic sky, to measure the 'cosmic shear' distortion of galaxy shapes by weak gravitational lensing. To measure the apparent shapes of those galaxies, we present an…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-08 Xiangchong Li , Yin Li , Richard Massey

Only galaxies bright enough and large enough to be unambiguously identified and measured are included in galaxy surveys used to estimate cosmic shear. We demonstrate that because gravitational lensing can scatter galaxies across the…

Cosmology and Nongalactic Astrophysics · Physics 2009-08-17 Fabian Schmidt , Eduardo Rozo , Scott Dodelson , Lam Hui , Erin Sheldon

Weak gravitational lensing measurements based on photometry are limited by shape noise, the variance in the unknown unlensed orientations of the source galaxies. If the source is a disk galaxy with a well-ordered velocity field, however,…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-08 David Wittman , Matthew Self

We derive expressions, in terms of "polar shapelets", for the image distortion operations associated with weak gravitational lensing. Shear causes galaxy shapes to become elongated, and is sensitive to the second derivative of the projected…

Astrophysics · Physics 2008-11-26 Richard Massey , Barnaby Rowe , Alexandre Refregier , David J. Bacon , Joel Berge

We implement the Elliptical Gauss-Laguerre (EGL) galaxy-shape measurement method proposed by Bernstein & Jarvis (2002) and quantify the shear recovery accuracy in weak lensing analysis. This method uses a deconvolution fitting scheme to…

Astrophysics · Physics 2008-11-26 Reiko Nakajima , Gary Bernstein

Weak gravitational lensing is one of the most important probes of the nature of dark matter and dark energy. In order to extract cosmological information from next-generation weak lensing surveys (e.g., Euclid, Roman, LSST, and CSST) as…

Measurement of the gravitational distortion of images of distant galaxies is rapidly becoming established as a powerful probe of the dark mass distribution in clusters of galaxies. With the advent of large mosaics of CCD's these methods…

Astrophysics · Physics 2007-05-23 Nick Kaiser , Gordon Squires , Greg Fahlman , David Woods , Tom Broadhurst

Weak lensing is emerging as a powerful observational tool to constrain cosmological models, but is at present limited by an incomplete understanding of many sources of systematic error. Many of these errors are multiplicative and depend on…

Weak lensing surveys exploit measurements of galaxy ellipticities. These measurements are subject to errors which degrade the cosmological information that can be extracted from the surveys. Here we propose a way of using the galaxy data…

Cosmology and Nongalactic Astrophysics · Physics 2013-08-07 Alberto Vallinotto , Scott Dodelson , Pengjie Zhang

In this brief review I consider the advances made in weak gravitational lensing over the last 8 years, concentrating on the large scales - cosmic shear. I outline the theoretical developments, observational status, and the challenges which…

Astrophysics · Physics 2015-05-13 Alan Heavens

We study the bias and scatter in mass measurements of galaxy clusters resulting from fitting a spherically-symmetric Navarro, Frenk & White model to the reduced tangential shear profile measured in weak lensing observations. The reduced…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-23 Matthew R. Becker , Andrey V. Kravtsov

We study the impact of systematic errors on planned weak lensing surveys and compute the requirements on their contributions so that they are not a dominant source of the cosmological parameter error budget. The generic types of error we…

Astrophysics · Physics 2010-04-06 Dragan Huterer , Masahiro Takada , Gary Bernstein , Bhuvnesh Jain

We use weak lensing shear measurements of six z>0.5 clusters of galaxies to derive the mean lensing redshift of the background galaxies used to measure the shear. Five of these clusters are compared to X-ray mass models and verify a mean…

Astrophysics · Physics 2009-11-10 D. Clowe , G. Luppino , N. Kaiser

The Shear TEsting Programme, STEP, is a collaborative project to improve the accuracy and reliability of all weak lensing measurements in preparation for the next generation of wide-field surveys. In this first STEP paper we present the…

Weak gravitational lensing of background galaxies offers an excellent opportunity to study the intervening distribution of matter. While much attention to date has focused on the two-point function of the cosmic shear, the three-point…

Astrophysics · Physics 2008-11-26 Scott Dodelson , Pengjie Zhang