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The analysis of the Lyman-alpha forest of absorption lines in quasar spectra has emerged as a potentially powerful technique to constrain the linear matter power spectrum. In most previous work, the amplitude of the ionizing background was…

Astrophysics · Physics 2009-11-11 Adam Lidz , Katrin Heitmann , Lam Hui , Salman Habib , Michael Rauch , Wallace L. W. Sargent

In this work we expand upon the Tomographic Absorption Reconstruction and Density Inference Scheme (TARDIS) in order to include multiple tracers while reconstructing matter density fields at Cosmic Noon (z ~ 2-3). In particular, we jointly…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-26 Benjamin Horowitz , Benjamin Zhang , Khee-Gan Lee , Robin Kooistra

We derive and numerically implement an algorithm for estimating the 3D power spectrum of the Lyman-$\alpha$ (Ly-$\alpha$) forest flux fluctuations. The algorithm exploits the unique geometry of Ly-$\alpha$ forest data to efficiently measure…

Cosmology and Nongalactic Astrophysics · Physics 2018-01-10 Andreu Font-Ribera , Patrick McDonald , Anže Slosar

Cosmological simulations with gas provide a detailed description of the intergalactic medium, making possible predictions of neutral hydrogen absorption in the spectra of background QSOs. We present results from a high-resolution…

Astrophysics · Physics 2009-10-28 Lars Hernquist , Neal Katz , David H. Weinberg , Jordi Miralda-Escude

We analyze the SDSS Ly-alpha forest P_F(k,z) measurement to determine the linear theory power spectrum. Our analysis is based on fully hydrodynamic simulations, extended using hydro-PM simulations. We account for the effect of absorbers…

We present a new, high resolution HST/GHRS spectrum of quasar Q0302-003, and use the HeII Lyman-$\alpha$ absorption, together with a high resolution Keck spectrum of the HI Lyman-$\alpha$ forest, to probe the distribution and ionization…

Astrophysics · Physics 2009-09-28 Craig J. Hogan , Scott F. Anderson , Martin H. Rugers

The Lyman-$\alpha$ (hereafter Ly-$\alpha$) forest is a probe of large-scale matter density fluctuations at high redshift, $z > 2.1$. It consists of HI absorption spectra along individual lines-of-sight. If the line-of-sight density is large…

We present DeepCHART (Deep learning for Cosmological Heterogeneity and Astrophysical Reconstruction via Tomography), a deep learning framework designed to reconstruct the three-dimensional dark matter density field at redshift $z=2.5$ from…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-02 Soumak Maitra , Matteo Viel , Girish Kulkarni

We present a field-based approach to the analysis of cosmic shear data to infer jointly cosmological parameters and the dark matter distribution. This forward modelling approach samples the cosmological parameters and the initial matter…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-17 Natalia Porqueres , Alan Heavens , Daniel Mortlock , Guilhem Lavaux

We use the LUQAS sample (Kim et al. 2004), a set of 27 high-resolution and high signal-to-noise QSO absorption spectra at a median redshift of z=2.25, and the data from Croft et al. (2002) at a median redshift of z=2.72, together with a…

Astrophysics · Physics 2008-11-26 Matteo Viel , Martin G. Haehnelt , Volker Springel

Cosmological studies of the Lyman-Alpha (Lya) forest typically constrain parameters using two-point statistics. However, higher-order statistics, such as the three-point function (or its Fourier counterpart, the bispectrum) offer additional…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-28 Roger de Belsunce , James M. Sullivan , Patrick McDonald

We present the first observations of foreground Lyman-$\alpha$ forest absorption from high-redshift galaxies, targeting 24 star-forming galaxies (SFGs) with $z\sim 2.3-2.8$ within a $5' \times 15'$ region of the COSMOS field. The transverse…

We present a semi-analytic model for the Lyman-$\alpha$ forest that is inspired by the Halo Model. This model is built on the absorption line decomposition of the forest. Flux correlations are decomposed into those within each absorption…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-10 Vid Iršič , Matthew McQuinn

We apply a linear Bayesian model to seismic tomography, a high-dimensional inverse problem in geophysics. The objective is to estimate the three-dimensional structure of the earth's interior from data measured at its surface. Since this…

Applications · Statistics 2013-12-11 Ran Zhang , Claudia Czado , Karin Sigloch

We investigate the properties of the Lyman alpha forest as predicted by numerical simulations for a range of currently viable cosmological models. This is done in order to understand the dependencies of the forest on cosmological…

Astrophysics · Physics 2009-10-31 M. E. Machacek , G. L. Bryan , A. Meiksin , P. Anninos , D. Thayer , M. L. Norman , Y. Zhang

We measure the power spectrum, P_F(k,z), of the transmitted flux in the Ly-alpha forest using 3035 high redshift quasar spectra from the Sloan Digital Sky Survey. This sample is almost two orders of magnitude larger than any previously…

The absorption lines observed in quasar spectra have given us a detailed picture of the intergalactic medium and the metal abundance and kinematics of high redshift galaxies. In this review, we present an introduction to the field, starting…

Astrophysics · Physics 2009-09-25 Jill Bechtold

New models of the attention-based random forests called LARF (Leaf Attention-based Random Forest) are proposed. The first idea behind the models is to introduce a two-level attention, where one of the levels is the "leaf" attention and the…

Machine Learning · Computer Science 2022-10-12 Andrei V. Konstantinov , Lev V. Utkin

Spatial fields in the Earth and environmental sciences are often available at multiple scales or resolutions. While coarse-scale data (e.g., from global circulation models) are often abundant, they lack the local detail provided by…

Methodology · Statistics 2026-04-01 Alejandro Calle-Saldarriaga , Paul F. V. Wiemann , Matthias Katzfuss

When performing cosmological inference, standard analyses of the Lyman-$\alpha$ (Ly$\alpha$) three-dimensional correlation functions only consider the information carried by the distinct peak produced by baryon acoustic oscillations (BAO).…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-14 Francesca Gerardi , Andrei Cuceu , Andreu Font-Ribera , Benjamin Joachimi , Pablo Lemos