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Weak gravitational lensing provides a unique method to map directly the distribution of dark matter in the universe and to measure cosmological parameters. This cosmic-shear technique is based on the measurement of the weak distortions that…

Astrophysics · Physics 2008-11-26 Alexandre Refregier

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 clustering of matter on cosmological scales is an essential probe for studying the physical origin and composition of our Universe. To date, most of the direct studies have focused on shear-shear weak lensing correlations, but it is…

Cosmology and Nongalactic Astrophysics · Physics 2010-07-26 Tobias Baldauf , Robert E. Smith , Uros Seljak , Rachel Mandelbaum

Alternative to weak lensing measurements through cosmic shear, we present a weak lensing convergence $\hat{\kappa}$ map reconstructed through cosmic magnification effect in DECaLS galaxies of the DESI imaging surveys DR9. This is achieved…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-05 Jian Qin , Pengjie Zhang , Haojie Xu , Yu Yu , Ji Yao , Ruijie Ma , Huanyuan Shan

We present a framework for analyzing weak gravitational lensing survey data, including lensing and source-density observables, plus spectroscopic redshift calibration data. All two-point observables are predicted in terms of parameters of a…

Astrophysics · Physics 2014-11-18 Gary M. Bernstein

We have shown that the cluster-mass reconstruction method which combines strong and weak gravitational lensing data, developed in the first paper in the series, successfully reconstructs the mass distribution of a simulated cluster. In this…

The surface mass density of a cluster of galaxies, and thus its total mass, can be estimated from its lens magnification. The magnification can be determined from the variation in number counts of its background galaxies. In the weak…

Astrophysics · Physics 2009-10-30 Eelco van Kampen

We present weak lensing mass estimates of seven shear-selected galaxy cluster candidates from the Deep Lens Survey. The clusters were previously identified as mass peaks in convergence maps of 8.6 sq. deg of R band imaging, and followed up…

Cosmology and Nongalactic Astrophysics · Physics 2009-08-17 Alexandra Abate , D. Wittman , V. E. Margoniner , S. L. Bridle , Perry Gee , J. Anthony Tyson , Ian P. Dell Antonio

A novel framework to construct an efficient sensing (measurement) matrix, called mixed adaptive-random (MAR) matrix, is introduced for directly acquiring a compressed image representation. The mixed sampling (sensing) procedure hybridizes…

Information Theory · Computer Science 2015-04-07 Jun Yang , Wei E. I. Sha , Hongyang Chao , Zhu Jin

Shape estimates that quantify the halo anisotropic mass distribution are valuable parameters that provide information on their assembly process and evolution. Measurements of the mean shapes for a sample of cluster-sized halos can be used…

The distortion of images of faint background galaxies by (weak) gravitational lensing can be used to measure the mass distribution of the deflector. The image distortions can be used to define a weighted mean of the mass inside a circular…

Astrophysics · Physics 2015-06-24 Peter Schneider

Model merging has recently emerged as a lightweight alternative to ensembling, combining multiple fine-tuned models into a single set of parameters with no additional training overhead. Yet, existing merging methods fall short of matching…

An appealing requirement from the well-known diffraction tomography (DT) exists for success reconstruction from few-view and limited-angle data. Inspired by the well-known compressive sensing (CS), the accurate super-resolution…

Computational Engineering, Finance, and Science · Computer Science 2009-04-20 Lianlin Li , Wenji Zhang , Fang Li

[Abridged] We present a comparison between weak-lensing (WL) and X-ray mass estimates of a sample of numerically simulated clusters. The sample consists on the 20 most massive objects at redshift z=0.25 and Mvir > 5 x 10^{14} Msun h^{-1}.…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 E. Rasia , M. Meneghetti , R. Martino , S. Borgani , A. Bonafede , K. Dolag , S. Ettori , D. Fabjan , C. Giocoli , P. Mazzotta , J. Merten , M. Radovich , L. Tornatore

We present an efficient and robust approach for extracting clusters of galaxies from weak lensing survey data and measuring their properties. We use simple, physically-motivated cluster models appropriate for such sparse, noisy data, and…

Astrophysics · Physics 2008-10-07 F. Feroz , P. J. Marshall , M. P. Hobson

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 sixteen current and emerging shear…

We present a survey of the cosmological applications of the next generation of weak lensing surveys, paying special attention to the computational challenges presented by the number of galaxies, $N_{gal} ~$ 10$^{5}$. We focus on optimal…

Astrophysics · Physics 2009-11-07 N. Padmanabhan , U. Seljak , U. L. Pen

Weak lensing measurements of cluster masses are necessary for calibrating mass-observable relations (MORs) to investigate the growth of structure and the properties of dark energy. However, the measured cluster shear signal varies at fixed…

Cosmology and Nongalactic Astrophysics · Physics 2013-04-04 Daniel Gruen , Gary M. Bernstein , Tsz Yan Lam , Stella Seitz

Flexion is a non-linear gravitational lensing effect that arises from gradients in the convergence and shear across an image. We derive a formalism that describes non-linear gravitational lensing by a circularly symmetric lens in the…

Cosmology and Nongalactic Astrophysics · Physics 2009-10-05 Paul Lasky , Chris Fluke

We present new results on the gravitational lensing shear and magnification power spectra obtained from numerical simulations of a flat cosmology with a cosmological constant. These results are of considerable interest since both the shear…

Astrophysics · Physics 2009-11-07 Andrew J. Barber , A. N. Taylor