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Isotropic functions of positions $\hat{\bf r}_1, \hat{\bf r}_2,\ldots, \hat{\bf r}_N$, i.e. functions invariant under simultaneous rotations of all the coordinates, are conveniently formed using spherical harmonics and Clebsch-Gordan…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-02 Robert N. Cahn , Zachary Slepian

Predicting the pose of objects from a single image is an important but difficult computer vision problem. Methods that predict a single point estimate do not predict the pose of objects with symmetries well and cannot represent uncertainty.…

Computer Vision and Pattern Recognition · Computer Science 2023-02-28 David M. Klee , Ondrej Biza , Robert Platt , Robin Walters

The Fourier transform of a dataset apodised with a window function is known as the Gabor transform. In this paper we extend the Gabor transform formalism to the sphere with the intention of applying it to CMB data analysis. The Gabor…

Astrophysics · Physics 2009-11-07 Frode K. Hansen , Krzysztof M. Gorski , Eric Hivon

We provide a method for fast and exact simulation of Gaussian random fields on spheres having isotropic covariance functions. The method proposed is then extended to Gaussian random fields defined over spheres cross time and having…

Computation · Statistics 2018-07-12 Francisco Cuevas , Emilio Porcu , Denis Allard

We propose nonparametric estimators for the second-order central moments of possibly anisotropic spherical random fields, within a functional data analysis context. We consider a measurement framework where each random field among an…

Statistics Theory · Mathematics 2022-06-28 Alessia Caponera , Julien Fageot , Matthieu Simeoni , Victor M. Panaretos

We aim to summarize the current state of knowledge regarding Galactic Faraday rotation in an all-sky map of the Galactic Faraday depth. For this we have assembled the most extensive catalog of Faraday rotation data of compact extragalactic…

We present a sound horizon independent measurement of the Hubble parameter using a multiprobe large-scale structure analysis. Removing the dependency on the sound horizon with a rescaling procedure at the matter power spectrum level, we…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-26 Zhiyu Lu , Théo Simon , Vivian Poulin , Yifu Cai

We present a comprehensive study of the regularity of the covariance matrix of a discretized field on the sphere. In a particular situation, the rank of the matrix depends on the number of pixels, the number of spherical harmonics, the…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-12 J. D. Bilbao-Ahedo , R. B. Barreiro , D. Herranz , P. Vielva , E. Martínez-González

There has been much recent interest in studying anisotropies in the astrophysical gravitational-wave (GW) background, as these could provide us with interesting new information about galaxy clustering and large-scale structure. However,…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-29 Alexander C. Jenkins , Joseph D. Romano , Mairi Sakellariadou

The efficient simulation of isotropic Gaussian random fields on the unit sphere is a task encountered frequently in numerical applications. A fast algorithm based on Markov properties and fast Fourier Transforms in 1d is presented that…

Numerical Analysis · Mathematics 2018-04-16 Peter E. Creasey , Annika Lang

We propose to measure the weak cosmic shear using the spatial derivatives of the galaxy surface brightness field. The measurement should be carried out in Fourier space, in which the point spread function (PSF) can be transformed to a…

Astrophysics · Physics 2009-11-11 Jun Zhang

We compute the real-space power spectrum and the redshift-space distortions of galaxies in the 2dF 100k galaxy redshift survey using pseudo-Karhunen-Loeve eigenmodes and the stochastic bias formalism. Our results agree well with those…

Astrophysics · Physics 2009-10-07 Max Tegmark , Andrew J. S. Hamilton , Yongzhong Xu

Direction dependent calibration and imaging is a vital part of producing deep, high fidelity, high-dynamic range radio images with a wide-field low-frequency array like LOFAR. Currently, state-of-the-art facet-based direction dependent…

Instrumentation and Methods for Astrophysics · Physics 2020-03-25 J. G. Albert , R. J. van Weeren , H. T. Intema , H. J. A. Röttgering

Gaussian particles provide a flexible framework for modelling and simulating three-dimensional star-shaped random sets. In our framework, the radial function of the particle arises from a kernel smoothing, and is associated with an…

We study the weak convergence (in the high-frequency limit) of the parameter estimators of power spectrum coefficients associated with Gaussian, spherical and isotropic random fields. In particular, we introduce a Whittle-type approximate…

Statistics Theory · Mathematics 2014-02-05 Claudio Durastanti , Xiaohong Lan , Domenico Marinucci

Using 1000 ray-tracing simulations for a {\Lambda}-dominated cold dark model in Sato et al. (2009), we study the covariance matrix of cosmic shear correlation functions, which is the standard statistics used in the previous measurements.…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Masanori Sato , Masahiro Takada , Takashi Hamana , Takahiko Matsubara

We use automated surface photometry and pattern classification techniques to morphologically classify galaxies. The two-dimensional light distribution of a galaxy is reconstructed using Fourier series fits to azimuthal profiles computed in…

Astrophysics · Physics 2009-11-07 S. C. Odewahn , S. H. Cohen , R. A. Windhorst , N. S. Philip

From the homotopy groups of three distinct octahedral spherical 3-manifolds we construct the isomorphic groups H of deck transformations acting on the 3-sphere. The H-invariant polynomials on the 3-sphere constructed by representation…

Mathematical Physics · Physics 2010-04-26 Peter Kramer

The weak lensing power spectrum carries cosmological information via its dependence on the growth of structure and on geometric factors. Since much of the cosmological information comes from scales affected by nonlinear clustering,…

Astrophysics · Physics 2010-11-02 Masahiro Takada , Bhuvnesh Jain

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