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Year 1 results of the Legacy Survey of Space and Time (LSST) will provide tighter constraints on small-scale cosmology, beyond the validity of linear perturbation theory. This heightens the demand for a computationally affordable…

Cosmology and Nongalactic Astrophysics · Physics 2024-08-27 Jonathan Gordon , Bernardo F. de Aguiar , João Rebouças , Guilherme Brando , Felipe Falciano , Vivian Miranda , Kazuya Koyama , Hans A. Winther

In modern randomized experiments, large-scale data collection increasingly yields rich baseline covariates and auxiliary information from multiple sources. Such information offers opportunities for more precise treatment effect estimation,…

Methodology · Statistics 2026-03-10 Wei Ma , Zeqi Wu , Zheng Zhang

The structural and dynamic properties of the dark matter halos, though an important ingredient in understanding large-scale structure formation, require more conservative particle resolution than those required by halo mass alone in a…

Cosmology and Nongalactic Astrophysics · Physics 2022-11-23 Sujatha Ramakrishnan , Premvijay Velmani

We propose the approximate Laplace approximation (ALA) to evaluate integrated likelihoods, a bottleneck in Bayesian model selection. The Laplace approximation (LA) is a popular tool that speeds up such computation and equips strong model…

Computation · Statistics 2021-10-07 David Rossell , Oriol Abril , Anirban Bhattacharya

In many astrophysical settings covariance matrices of large datasets have to be determined empirically from a finite number of mock realisations. The resulting noise degrades inference and precludes it completely if there are fewer…

Instrumentation and Methods for Astrophysics · Physics 2017-01-11 Benjamin Joachimi

This work presents the PORTALS framework, which leverages surrogate modeling and optimization techniques to enable the prediction of core plasma profiles and performance with nonlinear gyrokinetic simulations at significantly reduced cost,…

Naive estimates of the statistics of large scale structure and weak lensing power spectrum measurements that include only Gaussian errors exaggerate their scientific impact. Non-linear evolution and finite volume effects are both…

Cosmology and Nongalactic Astrophysics · Physics 2014-12-24 Emmanuel Schaan , Masahiro Takada , David N. Spergel

We compute covariance matrices for many observed estimates of the stellar mass function of galaxies from $z=0$ to $z\approx 4$, and for one estimate of the projected correlation function of galaxies split by stellar mass at $z\lesssim 0.5$.…

Astrophysics of Galaxies · Physics 2018-10-17 Andrew J. Benson

Over the next decade, improvements in cosmological parameter constraints will be driven by surveys of large-scale structure. Its inherent non-linearity suggests that significant information will be embedded in higher correlations beyond the…

Cosmology and Nongalactic Astrophysics · Physics 2017-07-19 Joyce Byun , Alexander Eggemeier , Donough Regan , David Seery , Robert E. Smith

We present a method for calculating large numbers of power spectra C_l and P(k) that accelerates CMBfast by a factor around 10^3 without appreciable loss of accuracy, then apply it to constrain 11 cosmological parameters from current Cosmic…

Astrophysics · Physics 2009-10-07 Max Tegmark , Matias Zaldarriaga , Andrew J. S. Hamilton

We propose a method for estimating a covariance matrix that can be represented as a sum of a low-rank matrix and a diagonal matrix. The proposed method compresses high-dimensional data, computes the sample covariance in the compressed…

Methodology · Statistics 2017-04-04 Gautam Sabnis , Debdeep Pati , Anirban Bhattacharya

Accurate covariance matrices are required for a reliable estimation of cosmological parameters from pseudo-power spectrum estimators. In this work, we focus on the analytical calculation of covariance matrices. We consider the case of…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-08 Étienne Camphuis , Karim Benabed , Silvia Galli , Éric Hivon , Marc Lilley

Covariance estimation becomes challenging in the regime where the number p of variables outstrips the number n of samples available to construct the estimate. One way to circumvent this problem is to assume that the covariance matrix is…

Probability · Mathematics 2012-06-14 Richard Y. Chen , Alex Gittens , Joel A. Tropp

Higher-order clustering statistics, like the galaxy bispectrum, can add complementary cosmological information to what is accessible with two-point statistics, like the power spectrum. While the standard way of measuring the bispectrum…

Cosmology and Nongalactic Astrophysics · Physics 2021-04-14 Joyce Byun , Andrea Oddo , Cristiano Porciani , Emiliano Sefusatti

We present here the cosmo-SLICS, a new suite of simulations specially designed for the analysis of current and upcoming weak lensing data beyond the standard two-point cosmic shear. We sample the $[\Omega_{\rm m}, \sigma_8, h, w_0]$…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-20 Joachim Harnois-Deraps , Benjamin Giblin , Benjamin Joachimi

According to recent findings [1,2], empirical covariance matrices deduced from financial return series contain such a high amount of noise that, apart from a few large eigenvalues and the corresponding eigenvectors, their structure can…

Statistical Mechanics · Physics 2009-11-07 Szilard Pafka , Imre Kondor

One of the major challenges in multivariate analysis is the estimation of population covariance matrix from sample covariance matrix (SCM). Most recent covariance matrix estimators use either shrinkage transformations or asymptotic results…

Methodology · Statistics 2019-12-10 Samruddhi Deshmukh , Amartansh Dubey

We measure the 3PCF of 300 halo catalogs from the Minerva simulations covering a total volume of $~1000 h^{-3} \mathrm{Gpc}^3$. Each 3PCF measurement includes all possible triangular configurations with sides between 20 and…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-21 A. Veropalumbo , A. Binetti , E. Branchini , M. Moresco , P. Monaco , A. Oddo , A. G. Sánchez , E. Sefusatti

We present $\it{CosmoPower}$, a suite of neural cosmological power spectrum emulators providing orders-of-magnitude acceleration for parameter estimation from two-point statistics analyses of Large-Scale Structure (LSS) and Cosmic Microwave…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-23 A. Spurio Mancini , D. Piras , J. Alsing , B. Joachimi , M. P. Hobson

As the determination of density fluctuations becomes more precise with larger surveys, it becomes more important to account for the increased covariance due to the non-linearity of the field. Here I have focussed on the galaxy density, with…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-12 Fabien Lacasa