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We present the 2-point function from Fast and Accurate Spherical Bessel Transformation (2-FAST) algorithm for a fast and accurate computation of integrals involving one or two spherical Bessel functions. These types of integrals occur when…

Cosmology and Nongalactic Astrophysics · Physics 2018-01-17 Henry S. Grasshorn Gebhardt , Donghui Jeong

We present a fast method for estimating the cosmic microwave background polarization power spectra using unbiased estimates of heuristically-weighted correlation functions. This extends the O(N_pix^(3/2)) method of Szapudi et al. (2001) to…

Astrophysics · Physics 2009-11-07 Gayoung Chon , Anthony Challinor , Simon Prunet , Eric Hivon , Istvan Szapudi

Conventional estimators of the anisotropic power spectrum and two-point correlation function (2PCF) adopt the `Yamamoto approximation', fixing the line-of-sight of a pair of galaxies to that of just one of its members. Whilst this is…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-16 Oliver H. E. Philcox , Zachary Slepian

We review the methodology for measurements of two point functions of the cosmological observables, both power spectra and correlation functions. For pseudo-$C_\ell$ estimators, we will argue that the window weighted overdensity field can…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-27 Sukhdeep Singh

We present a new class of estimators for computing small-scale power spectra and bispectra in configuration-space via weighted pair- and triple-counts, with no explicit use of Fourier transforms. Particle counts are truncated at $R_0\sim…

Cosmology and Nongalactic Astrophysics · Physics 2019-12-30 Oliver H. E. Philcox , Daniel J. Eisenstein

Though Fourier Transforms (FTs) are a common technique for finding correlation functions, they are not typically used in computations of the anisotropy of the two-point correlation function (2PCF) about the line of sight in wide-angle…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-28 Zachary Slepian , Daniel J. Eisenstein

This paper is designed to be a practical tool for constructing and investigating two-point correlation functions in defect conformal field theory, directly in physical space, between any two bulk primaries or between a bulk primary and a…

High Energy Physics - Theory · Physics 2021-05-12 Christopher P. Herzog , Abhay Shrestha

The two point angular correlation function is an excellent measure of structure in the universe. To extract from it the three dimensional power spectrum, one must invert Limber's Equation. Here we perform this inversion using a Bayesian…

Astrophysics · Physics 2008-11-26 Scott Dodelson , Enrique Gaztanaga

Recent theoretical and experimental studies have shown that squeezed states of light can be engineered to enhance the resolution of nonlinear optical measurements. Here, we analyze non-degenerate two-photon absorption signals obtained from…

Quantum Physics · Physics 2025-06-10 Gaurav Shukla , Shahram Panahiyan , Devendra Kumar Mishra , Frank Schlawin

The anisotropic 2-point correlation function (2PCF) of galaxies measures pairwise clustering as a function of the pair separation's angle to the line of sight. The latter is often defined as either the angle bisector of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-19 Zachary Slepian , Daniel J. Eisenstein

We show how to increase the accuracy of estimates of the two-point correlation function without sacrificing efficiency. We quantify the error of the pair-counts and of the Landy-Szalay estimator by comparing them with exact reference…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-26 Martin Kerscher

This paper introduces a highly efficient algorithm capable of jointly estimating scale and rotation between two images with sub-pixel precision. Image alignment serves as a critical process for spatially registering images captured from…

Computer Vision and Pattern Recognition · Computer Science 2025-09-30 Shinji Yamashita , Yuma Kinoshita , Hitoshi Kiya

The power spectrum, as a statistic in Fourier space, is commonly numerically calculated using the fast Fourier transform method to efficiently reduce the computational costs. To alleviate the systematic bias known as aliasing due to the…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-24 Yipeng Wang , Yu Yu

There has been a growing interest in wideband spectrum sensing due to its applications in cognitive radios and electronic surveillance. To overcome the sampling rate bottleneck for wideband spectrum sensing, in this paper, we study the…

Information Theory · Computer Science 2019-10-17 Linxiao Yang , Jun Fang , Huiping Duan , Hongbin Li

We develop a method for estimating the shear power spectra from weak lensing observations and test it on simulated data. Our method describes the shear field in terms of angular power spectra and cross correlation of the two shear modes…

Astrophysics · Physics 2008-11-26 Wayne Hu , Martin White

The usual fluid equations describing the large-scale evolution of mass density in the universe can be written as local in the density, velocity divergence, and velocity potential fields. As a result, the perturbative expansion in small…

Cosmology and Nongalactic Astrophysics · Physics 2016-06-01 Marcel Schmittfull , Zvonimir Vlah , Patrick McDonald

We developed a modification to the calculation of the two-point correlation function commonly used in the analysis of large scale structure in cosmology. An estimator of the two-point correlation function is constructed by contrasting the…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-20 Regina Demina , Sanha Cheong , Segev BenZvi , Otto Hindrichs

We report a measurement of the quadrupole power spectrum in the two degree field (2dF) QSO redshift (2QZ) survey. The analysis uses an algorithm parallel to that for the estimation of the standard monopole power spectrum without first…

In many applications data are measured or defined on a spherical manifold; spherical harmonic transforms are then required to access the frequency content of the data. We derive algorithms to perform forward and inverse spin spherical…

Astrophysics · Physics 2011-10-28 J. D. McEwen

We report a numerical calculation of the two-photon absorption coefficient of electrons in a binding potential using the real-time real-space higher-order difference method. By introducing random vector averaging for the intermediate state,…

Materials Science · Physics 2009-10-31 Yoshiyuki Kurokawa , Shintaro Nomura , Tadashi Takemori , Yoshinobu Aoyagi
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