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We present a simple analytic approximation for the covariance between pre-reconstruction galaxy power spectrum measurements and post-reconstruction two-point correlation functions. This cross-covariance is essential for joint analyses that…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-29 M. Maus , A. Baleato Lizancos , M. White , A. de Mattia , S. Chen

We present an algorithm enabling computation of the anisotropic redshift-space galaxy 3-point correlation function (3PCF) scaling as $N^2$, with $N$ the number of galaxies. Our previous work showed how to compute the isotropic 3PCF with…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-16 Zachary Slepian , Daniel J. Eisenstein

Current deep visual local feature detectors do not model the spatial uncertainty of detected features, producing suboptimal results in downstream applications. In this work, we propose two post-hoc covariance estimates that can be plugged…

Computer Vision and Pattern Recognition · Computer Science 2023-08-16 Javier Tirado-Garín , Frederik Warburg , Javier Civera

We consider the problem of estimating the covariance matrix of a random signal observed through unknown translations (modeled by cyclic shifts) and corrupted by noise. Solving this problem allows to discover low-rank structures masked by…

Statistics Theory · Mathematics 2020-11-11 Boris Landa , Yoel Shkolnisky

We present new predictions for the galaxy three-point correlation function (3PCF) using high-resolution dissipationless cosmological simulations of a flat LCDM Universe which resolve galaxy-size halos and subhalos. We create realistic mock…

Astrophysics · Physics 2008-11-26 Felipe Marin , Risa Wechsler , Joshua Frieman , Robert Nichol

Optimal analyses using the 2-point functions of large-scale structure probes require accurate covariance matrices. A covariance matrix of the 2-point function comprises the disconnected part and the connected part. While the connected…

Cosmology and Nongalactic Astrophysics · Physics 2019-01-14 Yin Li , Sukhdeep Singh , Byeonghee Yu , Yu Feng , Uros Seljak

We present an optimised multipole algorithm for computing the three-point correlation function (3PCF), tailored for application to large-scale cosmological datasets. The algorithm builds on a $in\, situ$ interpretation of correlation…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-21 Wenjie Ju , Longlong Feng , Zhiqi Huang , Xin Sun , Weishan Zhu

We analyze the quasar two-point correlation function (2pCF) within the redshift interval $0.8<z<2.2$ using a sample of 52303 quasars selected from the recent 7th Data Release of the Sloan Digital Sky Survey. Our approach to 2pCF uses a…

Cosmology and Nongalactic Astrophysics · Physics 2010-10-12 G. Ivashchenko , V. I. Zhdanov , A. V. Tugay

Two-point correlation functions are ubiquitous tools of modern cosmology, appearing in disparate topics ranging from cosmological inflation to late-time astrophysics. When the background spacetime is maximally symmetric, invariance…

General Relativity and Quantum Cosmology · Physics 2017-02-22 Oton H. Marcori , Thiago S. Pereira

The 3-Point Correlation Function (3PCF), which measures correlations between triplets of galaxies encodes information about peculiar velocities, which distort the observed positions of galaxies along the line of sight away from their true…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-09 Karolina Garcia , Zachary Slepian

We consider the problem of joint estimation of structured covariance matrices. Assuming the structure is unknown, estimation is achieved using heterogeneous training sets. Namely, given groups of measurements coming from centered…

Statistics Theory · Mathematics 2016-04-20 Ilya Soloveychik , Ami Wiesel

The covariance matrices of power-spectrum (P(k)) measurements from galaxy surveys are difficult to compute theoretically. The current best practice is to estimate covariance matrices by computing a sample covariance of a large number of…

Cosmology and Nongalactic Astrophysics · Physics 2016-02-03 David W. Pearson , Lado Samushia

We calculate the normalized angular three-point correlation function (3PCF), $q$, as well as the normalized angular skewness, $s_3$, assuming the small-angle approximation, for a biased mass distribution in flat and open cold-dark-matter…

Astrophysics · Physics 2009-10-31 Ari Buchalter , Marc Kamionkowski , Andrew H. Jaffe

Gaussian processes (GPs) are a popular model for spatially referenced data and allow descriptive statements, predictions at new locations, and simulation of new fields. Often a few parameters are sufficient to parameterize the covariance…

Machine Learning · Statistics 2021-01-01 Florian Gerber , Douglas W. Nychka

We investigate whether neighbor-density-weighted marked correlation functions (MCFs) can extract cosmological information beyond the standard redshift-space two-point correlation function (2PCF). Using the Kun suite of 129 $w_0w_a$CDM$+\sum…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-25 Xu Xiao , Xiao-Dong Li , Yiqi Huang , Le Zhang

Building on previous developments of a harmonic decomposition framework for computing the three-point correlation function (3PCF) of projected scalar fields over the sky, this work investigates how much cosmological information is contained…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-16 Sofia Samario-Nava , Alejandro Aviles , Juan Carlos Hidalgo

Accurately estimating the statistical properties of noise is important in data analysis for space-based gravitational wave detectors. Noise in different time-delay interferometry channels correlates with each other. Many studies often…

Instrumentation and Methods for Astrophysics · Physics 2025-06-18 Ya-Nan Li , Yi-Ming Hu , En-Kun Li

Cosmological large-scale structure analyses based on two-point correlation functions often assume a Gaussian likelihood function with a fixed covariance matrix. We study the impact on cosmological parameter estimation of ignoring the…

Cosmology and Nongalactic Astrophysics · Physics 2019-03-21 Darsh Kodwani , David Alonso , Pedro Ferreira

Surveys of cosmological large-scale structure (LSS) are sensitive to the presence of local primordial non-Gaussianity (PNG), and may be used to constrain models of inflation. Local PNG, characterized by fNL, the amplitude of the quadratic…