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In this third paper of a series on radio weak lensing for cosmology with the Square Kilometre Array, we scrutinise synergies between cosmic shear measurements in the radio and optical/near-IR bands for mitigating systematic effects. We…

Cosmology and Nongalactic Astrophysics · Physics 2018-09-19 Stefano Camera , Ian Harrison , Anna Bonaldi , Michael L. Brown

Weak gravitational lensing is a unique probe of the dark side of the universe: it provides a direct way to map the distribution of dark matter around galaxies, clusters of galaxies and on cosmological scales. Furthermore, the measurement of…

Astrophysics · Physics 2010-01-07 Henk Hoekstra , Bhuvnesh Jain

We improve the ERA(Ellipticity of Re-smeared Artificial image) method of PSF(Point Spread Function) correction in weak lensing shear analysis in order to treat realistic shape of galaxies and PSF. This is done by re-smearing PSF and the…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-31 Yuki Okura , Toshifumi Futamase

Optical weak lensing surveys have become a powerful tool for precision cosmology, but remain subject to systematic effects that can severely bias cosmological parameter estimates if not carefully removed. We discuss the possibility of…

Cosmology and Nongalactic Astrophysics · Physics 2018-06-22 Philip Bull , Ian Harrison , Eric Huff

We present a numerical investigation of nonlinear cluster lens reconstruction using weak lensing mass mapping. Recent advances in imaging and shear estimation have pushed reliable reduced shear measurements closer to cluster cores, making…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-23 Yuan Shi , Li Cui

We introduce a new method for constraining the redshift distribution of a set of galaxies, using weak gravitational lensing shear. Instead of using observed shears and redshifts to constrain cosmological parameters, we ask how well the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 D. Wittman , W. A. Dawson

Weak shear maps of the outer regions of clusters have been successfully used to map the distribution of mass at large radii from the cluster center. The typical smoothing lengths employed thus far preclude the systematic study of the…

Astrophysics · Physics 2015-06-24 Priyamvada Natarajan , Jean-Paul Kneib

The Cosmological Principle is a cornerstone of the standard model of cosmology and shapes how we view the Universe and our place within it. It is imperative, then, to devise multiple observational tests which can identify and quantify…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-13 James Adam , Roy Maartens , Julien Larena , Chris Clarkson

We present a new shear estimator for weak lensing observations which properly accounts for the effects of a realistic point spread function (PSF). Images of faint galaxies are subject to gravitational shearing followed by smearing with the…

Astrophysics · Physics 2009-10-31 Nick Kaiser

Kinematic weak lensing describes the distortion of a galaxy's projected velocity field due to lensing shear, an effect recently reported for the first time by Gurri et al. based on a sample of 18 galaxies at $z \sim 0.1$. In this paper, we…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-08 Brian DiGiorgio , Kevin Bundy , Kyle B. Westfall , Alexie Leauthaud , David Stark

This review forms the Weak Lensing part of the Saas-Fee Advanced Course on Gravitational Lensing. It describes the basicsm applications and results of weak lensing. Contents: (1) Introduction (2) The principles of weak gravitational lensing…

Astrophysics · Physics 2009-11-11 Peter Schneider

Weak gravitational lensing induces flux dependent fluctuations in the observed galaxy number density distribution. This cosmic magnification (magnification bias) effect in principle enables lensing reconstruction alternative to cosmic shear…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-04 Ruijie Ma , Pengjie Zhang , Yu Yu , Jian Qin

The measurement of cosmic shear using weak gravitational lensing is a challenging task that involves a number of complicated procedures. We study in detail the systematic errors in the measurement of weak lensing Minkowski Functionals…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Masato Shirasaki , Naoki Yoshida

The complete 10-year survey from the Large Synoptic Survey Telescope (LSST) will image $\sim$ 20,000 square degrees of sky in six filter bands every few nights, bringing the final survey depth to $r\sim27.5$, with over 4 billion well…

The use of large, X-ray selected galaxy cluster catalogues for cosmological analyses requires a thorough understanding of the X-ray mass estimates. Weak gravitational lensing is an ideal method to shed light on such issues, due to its…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-05 Melanie Simet , Nicholas Battaglia , Rachel Mandelbaum , Uroš Seljak

We measure the weak lensing shear around galaxy troughs, i.e. the radial alignment of background galaxies relative to underdensities in projections of the foreground galaxy field over a wide range of redshift in Science Verification data…

It is usually assumed that the ellipticity power spectrum measured in weak lensing observations can be expressed as an integral over the underlying matter power spectrum. This is true at second order in the gravitational potential. We…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Elisabeth Krause , Christopher M. Hirata

Shear estimation bias from galaxy detection and blending identification is now recognized as an issue for ongoing and future weak lensing surveys. Currently, the empirical approach to correcting for this bias involves numerically shearing…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-29 Xiangchong Li , Rachel Mandelbaum

Metacalibration is a state-of-the-art technique for measuring weak gravitational lensing shear from well-sampled galaxy images. We investigate the accuracy of shear measured with metacalibration from fitting elliptical Gaussians to…

Instrumentation and Methods for Astrophysics · Physics 2021-03-03 Arun Kannawadi , Erik Rosenberg , Henk Hoekstra

We report a detection of the coherent distortion of faint galaxies arising from gravitational lensing by foreground structures. This ``cosmic shear'' is potentially the most direct measure of the mass power spectrum, as it is unaffected by…

Astrophysics · Physics 2011-05-05 David Bacon , Alexandre Refregier , Richard Ellis