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We present a study of the dependencies of shear bias on simulation (input) and measured (output) parameters, noise, point-spread function anisotropy, pixel size, and the model bias coming from two different and independent galaxy shape…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-14 Arnau Pujol , Florent Sureau , Jerome Bobin , Frederic Courbin , Marc Gentile , Martin Kilbinger

We investigate the value of the near-infrared imaging from upcoming surveys for constraining the ellipticities of galaxies. We select galaxies between 0.5 < z < 3 that are brighter than expected Euclid sensitivity limits from the GOODS-S…

Astrophysics of Galaxies · Physics 2018-10-31 Bomee Lee , Ranga-Ram Chary , Edward L. Wright

We present the results of attempts to detect the ellipticity of dark matter halos using galaxy-galaxy weak lensing with SDSS data. We use 2,020,256 galaxies brighter than r=19 with photometric redshifts (divided into colour and luminosity…

We discuss the galaxy-galaxy-mass three-point correlation function and show how to measure it with weak gravitational lensing. The method entails choosing a large of pairs of foreground lens galaxies and constructing a mean shear map with…

Astrophysics · Physics 2009-11-10 David E. Johnston

We propose a precise ellipsometric method for the investigation of coherent light with a small ellipticity. The main feature of this method is the use of compensators with phase delays providing the maximum accuracy of measurements for the…

Instrumentation and Detectors · Physics 2017-06-21 Nazar Al-wassiti , Evelina Bibikova , Nataliya Kundikova

In this paper, we propose a method for initial camera pose estimation from just a single image which is robust to viewing conditions and does not require a detailed model of the scene. This method meets the growing need of easy deployment…

Computer Vision and Pattern Recognition · Computer Science 2022-03-10 Matthieu Zins , Gilles Simon , Marie-Odile Berger

Cosmological simulations predict that galaxies are embedded into triaxial dark matter haloes, which appear approximately elliptical in projection. Weak gravitational lensing allows us to constrain these halo shapes and thereby test the…

In safety-critical applications like medical diagnosis, certainty associated with a model's prediction is just as important as its accuracy. Consequently, uncertainty estimation and reduction play a crucial role. Uncertainty in predictions…

Image and Video Processing · Electrical Eng. & Systems 2023-09-12 Abhishek Singh Sambyal , Narayanan C. Krishnan , Deepti R. Bathula

As the volume and quality of modern galaxy surveys increase, so does the difficulty of measuring the cosmological signal imprinted in galaxy shapes. Weak gravitational lensing sourced by the most massive structures in the Universe generates…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-04 Benjamin Remy , Francois Lanusse , Jean-Luc Starck

Ellipsoid fitting is of general interest in machine vision, such as object detection and shape approximation. Most existing approaches rely on the least-squares fitting of quadrics, minimizing the algebraic or geometric distances, with…

Computer Vision and Pattern Recognition · Computer Science 2021-10-27 Zhao Mingyang , Jia Xiaohong , Ma Lei , Qiu Xinlin , Jiang Xin , Yan Dong-Ming

We study the effects of ellipticity in lens galaxies and external tidal shear from neighboring objects on the statistics of strong gravitational lenses. For isothermal lens galaxies normalized so that the Einstein radius is independent of…

Astrophysics · Physics 2009-11-10 Dragan Huterer , Chuck Keeton , Chung-Pei Ma

Alignments in the angular momentum vectors of galaxies can induce large scale correlations in their projected orientations. Such alignments arise from the tidal torques exerted on neighboring proto-galaxies by the smoothly varying shear…

Astrophysics · Physics 2009-11-06 Priyamvada Natarajan , Robert G. Crittenden , Ue-Li Pen , Tom Theuns

Strong gravitational lensing offers constraints on the Hubble constant that are independent of other methods. However, those constraints are subject to uncertainties in lens models. Previous studies suggest that using an elliptical power…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-02 Dilys Ruan , Charles R. Keeton

In computer vision, camera pose estimation from correspondences between 3D geometric entities and their projections into the image has been a widely investigated problem. Although most state-of-the-art methods exploit low-level primitives…

Computer Vision and Pattern Recognition · Computer Science 2023-06-16 Vincent Gaudillière , Gilles Simon , Marie-Odile Berger

Most estimators collapse all uncertainty modes into a single confidence score, preventing reliable reasoning about when to allocate more compute or adjust inference. We introduce Uncertainty-Guided Inference-Time Selection, a lightweight…

Computer Vision and Pattern Recognition · Computer Science 2025-11-18 Divake Kumar , Patrick Poggi , Sina Tayebati , Devashri Naik , Nilesh Ahuja , Amit Ranjan Trivedi

The weak gravitational lensing effect, small coherent distortions of galaxy images by means of a gravitational tidal field, can be used to study the relation between the matter and galaxy distribution. In this context, weak lensing has so…

Astrophysics · Physics 2014-11-18 P. Simon , P. Watts , P. Schneider , H. Hoekstra , M. D. Gladders , H. K. C. Yee , B. C. Hsieh , H. Lin

Noise is an unavoidable part of most measurements which can hinder a correct interpretation of the data. Uncertainties propagate in the data analysis and can lead to biased results even in basic descriptive statistics such as the central…

Instrumentation and Methods for Astrophysics · Physics 2023-11-27 Lorenzo Rimoldini

We develop a new approach to extracting model-independent information from observations of strong gravitational lenses. The approach is based on the generic properties of images near the fold and cusp catastrophes in caustics and critical…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-04 Jenny Wagner , Matthias Bartelmann

The shapes of galaxies can be quantified by ratios of their quadrupole moments. For faint galaxies, observational noise can make the denominator close to zero, so the ratios become ill-defined. Knowledge of these ratios (i.e. their measured…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-18 Holger Israel , Thomas D. Kitching , Richard Massey

We measure seeing-corrected ellipticities for 2 x 10^6 galaxies with magnitude R<23 in 12 widely separated fields totalling 75 deg^2 of sky. At angular scales >30\arcmin, ellipticity correlations are detected at high significance and…

Astrophysics · Physics 2015-06-24 M. Jarvis , G. Bernstein , B. Jain , P. Fischer , D. Smith , J. A. Tyson , D. Wittman
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