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Lyman-$\alpha$(Ly$\alpha$) forest in the spectra of distant quasars encodes the information of the underlying cosmic density field at smallest scales. The modelling of the upcoming large and high-fidelity forest data using cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-10 Bhaskar Arya

Observations of the Lyman-$\alpha$ (Ly$\alpha$) forest in spectra of distant quasars enable us to probe the matter power spectrum at relatively small scales. With several upcoming surveys, it is expected that there will be a many-fold…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-15 Bhaskar Arya , Tirthankar Roy Choudhury , Aseem Paranjape , Prakash Gaikwad

We analyze the flux power spectrum and its covariance using simulated Lyman alpha forests. We find that pseudo-hydro techniques are good approximations of hydrodynamical simulations at high redshift. However, the pseudo-hydro techniques…

Astrophysics · Physics 2009-11-11 Hu Zhan , Romeel Dave , Daniel Eisenstein , Neal Katz

Observations of the Lyman-$\alpha$ forest in distant quasar spectra with upcoming surveys are expected to provide significantly larger and higher-quality datasets. To interpret these datasets, it is imperative to develop efficient…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-13 Bhaskar Arya , Tirthankar Roy Choudhury , Aseem Paranjape , Prakash Gaikwad

We present 40 fully hydrodynamical numerical simulations of the intergalactic gas that gives rise to the Ly-alpha forest. We make artificial spectra from each and measure three output parameters: the mean flux, a measure of the most common…

We test a method to reduce unwanted sample variance when predicting Lyman-$\alpha$ (ly$\alpha$) forest power spectra from cosmological hydrodynamical simulations. Sample variance arises due to sparse sampling of modes on large scales and…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-16 Lauren Anderson , Andrew Pontzen , Andreu Font-Ribera , Francisco Villaescusa-Navarro , Keir K. Rogers , Shy Genel

The distribution of absorption lines in the spectra of distant quasars, called the Lyman-$\alpha$ (Ly-$\alpha$) forest, is a unique probe of cosmology and the intergalactic medium at high redshifts and small scales. The statistical power of…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-02 Roger de Belsunce , Mikhail M. Ivanov , James M. Sullivan , Kazuyuki Akitsu , Shi-Fan Chen

We use hydrodynamic simulations to predict correlations between Lya forest absorption and galaxies at redshift z~3. The probability distribution function (PDF) of Lya flux decrements shifts systematically towards higher values in the…

Astrophysics · Physics 2009-11-07 Juna A. Kollmeier , David H. Weinberg , Romeel Dave' , Neal Katz

We study the statistics of the Lyman-$\alpha$ forest in a flat LCDM cosmology with the N-body + Eulerian hydrodynamics code Nyx. We produce a suite of simulations, covering the observationally relevant redshift range $2 \leq z \leq 4$. We…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-24 Zarija Lukić , Casey Stark , Peter Nugent , Martin White , Avery Meiksin , Ann Almgren

We use the Ly-$\alpha$ Mass Association Scheme (LyMAS; Peirani et al. 2014) to predict cross-correlations at $z=2.5$ between dark matter halos and transmitted flux in the Ly-$\alpha$ forest, and compare to cross-correlations measured for…

In this work, we analyze the Lyman-$\alpha$ forest in cosmological hydrodynamical simulations of chameleon-type f(R) gravity with the goal to assess whether the impact of such models is detectable in absorption line statistics. We carry out…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-23 Christian Arnold , Ewald Puchwein , Volker Springel

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 review recent developments in the theory of the Lyman-alpha forest and their implications for the role of the forest as a test of cosmological models. Simulations predict a relatively tight correlation between the local Lya optical depth…

Astrophysics · Physics 2009-11-07 David H. Weinberg , Romeel Dav'e , Neal Katz , Juna A. Kollmeier

We explore the feasibility of using Lyman-$\alpha$ (Ly$\alpha$) forests to calibrate the ensemble redshift distribution of the high-redshift tail ($2<z<3$) of photometric galaxies. We use \texttt{CoLoRe} simulations to create mock DESI…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-12 Qianjun Hang , Laura Casas , William d'Assignies , Wynne Turner , Andreu Font-Ribera , Benjamin Joachimi

The one-dimensional flux power spectrum (P1D) of the Lyman-$\alpha$ forest probes small-scale structure in the intergalactic medium (IGM) and is therefore sensitive to a variety of cosmological and astrophysical parameters. These include…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-22 Meagan Herbold , Naim Göksel Karaçaylı , Paul Martini

We use a large set of cosmological smoothed particle hydrodynamics (SPH) simulations to examine the effect of mass resolution and box size on synthetic Lya forest spectra at 2 \leq z \leq 5. The mass resolution requirements for the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 James S. Bolton , George D. Becker

The Ly$\alpha$ forest, a series of HI absorption lines in the quasar spectra, is a powerful tool for probing the large-scale structure of the intergalactic medium. Its three-dimensional (3D) correlation and cross-correlations with quasars…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-23 Koichiro Nakashima , Atsushi J. Nishizawa , Kentaro Nagamine , Yuri Oku , Ikkoh Shimizu

The Ly$\alpha$ forest provides one of the best means of mapping large-scale structure at high redshift, including our tightest constraint on the distance-redshift relation before cosmic noon. We describe how the large-scale correlations in…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-02 Shi-Fan Chen , Zvonimir Vlah , Martin White

[abridged] We describe LyMAS (Ly-alpha Mass Association Scheme), a method of predicting clustering statistics in the Ly-alpha forest on large scales from moderate resolution simulations of the dark matter distribution, with calibration from…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-05 Sébastien Peirani , David H. Weinberg , Stéphane Colombi , Jérémy Blaizot , Yohan Dubois , Christophe Pichon

The inference of astrophysical and cosmological properties from the Lyman-$\alpha$ forest conventionally relies on summary statistics of the transmission field that carry useful but limited information. We present a deep learning framework…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-11 Parth Nayak , Michael Walther , Daniel Gruen , Sreyas Adiraju
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