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Accurate estimation of the covariance matrix of cosmic shear statistics is essential for cosmological analyses using current and upcoming wide-area weak lensing surveys. In this work, we investigate analytical methods for computing the…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-18 Kosuke Nagura , Ryo Terasawa , Taisei Terawaki , Masahiro Takada

We propose an Analytical method of Blind Separation (ABS) of cosmic magnification from the intrinsic fluctuations of galaxy number density in the observed galaxy number density distribution. The ABS method utilizes the different dependences…

Cosmology and Nongalactic Astrophysics · Physics 2017-10-27 Xinjuan Yang , Jun Zhang , Yu Yu , Pengjie Zhang

We update the field-level inference code KARMMA to enable tomographic forward-modelling of shear maps. Our code assumes a lognormal prior on the convergence field, and properly accounts for the cross-covariance in the lensing signal across…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-11 Supranta S. Boruah , Pier Fiedorowicz , Eduardo Rozo

Convergence maps of the integrated matter distribution are a key science result from weak gravitational lensing surveys. To date, recovering convergence maps has been performed using a planar approximation of the celestial sphere. However,…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-16 Christopher G. R. Wallis , Matthew A. Price , Jason D. McEwen , Thomas D. Kitching , Boris Leistedt , Antoine Plouviez

Deep learning has been successfully demonstrated in MRI reconstruction of accelerated acquisitions. However, its dependence on representative training data limits the application across different contrasts, anatomies, or image sizes. To…

Signal Processing · Electrical Eng. & Systems 2019-09-20 Chaoping Zhang , Florian Dubost , Marleen de Bruijne , Stefan Klein , Dirk H. J. Poot

Weak-lensing mass-mapping algorithms, which reconstruct the convergence field from galaxy shear measurements, are crucial for extracting higher-order statistics to constrain cosmological parameters. However, only limited research has…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-28 Andreas Tersenov , Lucie Baumont , Jean-Luc Starck , Martin Kilbinger

Retrieval augmented generation (RAG) has transformed text based question answering, yet its extension to visual domains remains hindered by fundamental challenges: bridging the modality gap between image queries and text heavy knowledge…

Computer Vision and Pattern Recognition · Computer Science 2026-04-27 Parthaw Goswami , Jaynto Goswami Deep

The exact cover problem is an NP-complete problem with broad applications. Studies show that although applying the Quantum Approximate Optimization Algorithm (QAOA) to this problem can yield improved solution quality with deeper circuit…

Quantum Physics · Physics 2025-09-16 Xiao-Hui Ni , Jia-Cheng Fan , Ling-Xiao Li , Zi-Wen Huang , Su-Juan Qin , Bing-Jie Xu , Wei-Huang , Fei Gao

We present a general linear algorithm for measuring the surface mass density 1-\kappa from the observable reduced shear g=\gamma/(1-\kappa) in the strong lensing regime. We show that in general, the observed polarization field can be…

Astrophysics · Physics 2009-10-31 Ue-Li Pen

We present an algorithm using Principal Component Analysis (PCA) to subtract galaxies from imaging data, and also two algorithms to find strong, galaxy-scale gravitational lenses in the resulting residual image. The combined method is…

Instrumentation and Methods for Astrophysics · Physics 2015-06-19 R. Joseph , F. Courbin , R. B. Metcalf , C. Giocoli , P. Hartley , N. Jackson , F. Bellagamba , J. -P. Kneib , L. Koopmans , G. Lemson , M. Meneghetti , G. Meylan , M. Petkova , S. Pires

Using higher-order statistics to capture cosmological information from weak lensing surveys often requires a transformation of observed shear to a measurement of the convergence signal. This inverse problem is complicated by noise and…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-25 Nisha Grewal , Joe Zuntz , Tilman Tröster

Context. Weak gravitational lensing is a powerful probe of large-scale structure and cosmology. Most commonly, second-order correlations of observed galaxy ellipticities are expressed as a projection of the matter power spectrum,…

Cosmology and Nongalactic Astrophysics · Physics 2010-08-25 Martin Kilbinger

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

Now that weak lensing signals on the order of a percent are actively being searched for (cosmic shear, galaxy-galaxy lensing, large radii in clusters...) it is important to investigate how accurately weak shears can be determined. Many…

Astrophysics · Physics 2016-08-30 K. Kuijken

Weak gravitational lensing is one of the few direct methods to map the dark-matter distribution on large scales in the Universe, and to estimate cosmological parameters. We study a Bayesian inference problem where the data covariance…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-01 Martin Kilbinger , Emille E. O. Ishida , Jessi Cisewski-Kehe

Noise bias is a significant source of systematic error in weak gravitational lensing measurements that must be corrected to satisfy the stringent standards of modern imaging surveys in the era of precision cosmology. This paper reviews the…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-09 Xiangchong Li , Rachel Mandelbaum , The LSST Dark Energy Science Collaboration

The existence of galaxy intrinsic clustering severely hampers the weak lensing reconstruction from cosmic magnification. In paper I \citep{Yang2011}, we proposed a minimal variance estimator to overcome this problem. By utilizing the…

Cosmology and Nongalactic Astrophysics · Physics 2016-09-21 Xinjuan Yang , Pengjie Zhang , Jun Zhang , Yu Yu

The locally competitive algorithm (LCA) can solve sparse coding problems across a wide range of use cases. Recently, convolution-based LCA approaches have been shown to be highly effective for enhancing robustness for image recognition…

Computer Vision and Pattern Recognition · Computer Science 2025-05-01 Geoffrey Kasenbacher , Felix Ehret , Gerrit Ecke , Sebastian Otte

We propose and evaluate a new MRI reconstruction method named LORAKI that trains an autocalibrated scan-specific recurrent neural network (RNN) to recover missing k-space data. Methods like GRAPPA, SPIRiT, and AC-LORAKS assume that k-space…

Image and Video Processing · Electrical Eng. & Systems 2019-04-25 Tae Hyung Kim , Pratyush Garg , Justin P. Haldar

This paper proposes scalable and fast algorithms for solving the Robust PCA problem, namely recovering a low-rank matrix with an unknown fraction of its entries being arbitrarily corrupted. This problem arises in many applications, such as…

Optimization and Control · Mathematics 2013-10-21 Zhouchen Lin , Minming Chen , Yi Ma