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We propose a method for recovering the shape of the mass power spectrum on large scales from the transmission fluctuations of the Lyman-alpha forest, which takes into account directly redshift-space distortions. The procedure, in…

Astrophysics · Physics 2009-10-30 Lam Hui

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

High resolution N-body simulations of cold dark matter (CDM) models predict that galaxies and clusters have cuspy halos with excessive substructure. Observations reveal smooth halos with central density cores. One possible resolution of…

Astrophysics · Physics 2015-09-23 Vijay K. Narayanan , David N. Spergel , Romeel Davé , Chung-Pei Ma

Prediction in high dimensional settings is difficult due to large by number of variables relative to the sample size. We demonstrate how auxiliary "co-data" can be used to improve the performance of a Random Forest in such a setting.…

Applications · Statistics 2017-06-05 Dennis E. te Beest , Steven W. Mes , Ruud H. Brakenhoff , Mark A. van de Wiel

Trend filtering---first introduced into the astronomical literature in Paper I of this series---is a state-of-the-art statistical tool for denoising one-dimensional signals that possess varying degrees of smoothness. In this work, we…

Instrumentation and Methods for Astrophysics · Physics 2022-02-01 Collin A. Politsch , Jessi Cisewski-Kehe , Rupert A. C. Croft , Larry Wasserman

On large scales, the Lyman-$\alpha$ forest provides insights into the expansion history of the Universe, while on small scales, it imposes strict constraints on the growth history, the nature of dark matter, and the sum of neutrino masses.…

We present some statistical features of the large number of \lya absorption lines detected in high redshift quasar spectra, obtained by using the multifractal approach. In the analysed sample of 12 QSO sight--lines, 11 show scaling…

Astrophysics · Physics 2007-05-23 S. Savaglio , V. Carbone

Random forest (RF) missing data algorithms are an attractive approach for dealing with missing data. They have the desirable properties of being able to handle mixed types of missing data, they are adaptive to interactions and nonlinearity,…

Machine Learning · Statistics 2017-01-23 Fei Tang , Hemant Ishwaran

Large surveys for Lyman-alpha emitting (LAE) galaxies have been proposed as a new method for measuring clustering of the galaxy population at high redshift with the goal of determining cosmological parameters. However, Lyman-alpha radiative…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Bradley Greig , Eiichiro Komatsu , J. Stuart B. Wyithe

Deep learning (DL) has been shown to outperform traditional, human-defined summary statistics of the Ly{\alpha} forest in constraining key astrophysical and cosmological parameters owing to its ability to tap into the realm of non-Gaussian…

Instrumentation and Methods for Astrophysics · Physics 2025-10-24 Parth Nayak , Michael Walther , Daniel Gruen

We present an analysis of Si III absorption and its effect on the 1D Ly$\alpha$ forest power spectrum using the Sherwood-Relics hydrodynamical simulation suite. In addition to oscillations from the Ly$\alpha$--Si III cross correlation that…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-02 Ke Ma , James S. Bolton , Vid Irsic , Prakash Gaikwad , Ewald Puchwein

Small-scale correlations measured in the Lyman-$\alpha$ (Ly$\alpha$) forest encode information about the intergalactic medium and the primordial matter power spectrum. In this article, we present and implement a simple method to measure the…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-27 Marie Lynn Abdul-Karim , Eric Armengaud , Guillaume Mention , Solène Chabanier , Corentin Ravoux , Zarija Lukić

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

The Lyman-alpha forest has opened a new redshift regime for cosmological investigation. At z > 2 it provides a unique probe of cosmic geometry and an independent constraint on dark energy that is not subject to standard candle or ruler…

Astrophysics · Physics 2009-11-13 Andrew R. Marble , Kristoffer A. Eriksen , Chris D. Impey , Lei Bai , Lance Miller

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

The Lyman-alpha forest is a unique probe of large-scale matter density fluctuations at high redshift (z > 2). It is possible to obtain 3D maps of the matter distribution from Lyman-alpha data, using tomographic reconstruction methods. Here,…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-16 Corentin Ravoux

The full-shape correlations of the Lyman alpha (Ly$\alpha$) forest contain a wealth of cosmological information through the Alcock-Paczy\'{n}ski effect. However, these measurements are challenging to model without robustly testing and…

Massive spectroscopic surveys of high-redshift quasars yield large numbers of correlated Lyman {\alpha} absorption spectra that can be used to measure large-scale structure. Simulations of these surveys are required to accurately interpret…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Andreu Font-Ribera , Patrick McDonald , Jordi Miralda-Escudé
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