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The linear matter power spectrum is an essential ingredient in all theoretical models for interpreting large-scale-structure observables. Although Boltzmann codes such as CLASS or CAMB are very efficient at computing the linear spectrum,…

Cosmology and Nongalactic Astrophysics · Physics 2022-06-20 Giovanni Aricò , Raul E. Angulo , Matteo Zennaro

We present a comprehensive analysis of high resolution hydrodynamic simulations in terms of Lyman-alpha and Lyman-beta one dimensional flux power spectra ($P_{\alpha\alpha}$ and $P_{\beta\beta}$). In particular, we focus on the behaviour…

Cosmology and Nongalactic Astrophysics · Physics 2014-12-15 Vid Iršič , Matteo Viel

The Lyman alpha forest power spectrum has been measured on large scales by the BOSS survey in SDSS-III at $z\sim 2.3$, has been shown to agree well with linear theory predictions, and has provided the first measurement of Baryon Acoustic…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-16 Andreu Arinyo-i-Prats , Jordi Miralda-Escudé , Matteo Viel , Renyue Cen

We measure the matter power spectrum from the Lyman-alpha forest of 31 quasar spectra spanning the redshift range of 1.6-3.6. The optical depth, $\tau$, for absorption of the intergalactic medium is obtained from the flux using the…

Astrophysics · Physics 2009-11-11 S. Zaroubi , M. Viel , A. Nusser , M. Haehnelt , T. -S. Kim

We compare and validate COLA (COmoving Lagrangian Acceleration) simulations against existing emulators in the literature, namely Bacco and Euclid Emulator 2. Our analysis focuses on the non-linear response function, i.e., the ratio between…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-28 Guilherme Brando , Bartolomeo Fiorini , Kazuya Koyama , Hans A. Winther

An accurate theoretical template of the redshift-space galaxy power spectrum, if applicable out to nonlinear scales, enables us to extract more stringent and robust constraints on cosmological parameters from the measured galaxy clustering.…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-20 Yosuke Kobayashi , Takahiro Nishimichi , Masahiro Takada , Ryuichi Takahashi , Ken Osato

We present an effective field theory (EFT) approach to extract fundamental cosmological parameters from the Lyman-alpha forest flux fluctuations as an alternative to the standard simulation-based techniques. As a first application, we…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-21 Mikhail M. Ivanov , Michael W. Toomey , Naim Göksel Karaçaylı

The 1D Ly-$\alpha$ forest flux power spectrum $P_{\mathrm{1D}}$ is sensitive to scales smaller than a typical galaxy survey, and hence ties to the intergalactic medium's thermal state, suppression from neutrino masses and new dark matter…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-17 Naim Göksel Karaçaylı , Andreu Font-Ribera , Nikhil Padmanabhan

We present the PRIYA suite of cosmological simulations, based on the code and hydrodynamic model of the ASTRID simulation, and designed for cosmological analyses of the Lyman-$\alpha$ forest. Our simulation suite spans a $9$-dimensional…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-04 Simeon Bird , Martin Fernandez , Ming-Feng Ho , Mahdi Qezlou , Reza Monadi , Yueying Ni , Nianyi Chen , Rupert Croft , Tiziana Di Matteo

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 two subsets of 2000 and 1000 Quijote simulations to build two power spectrum emulators, allowing for fast computations of the non-linear matter power spectrum. The first emulator is built in terms of seven cosmological parameters:…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-09 Andrei Lazanu

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

The power spectrum of density fluctuations is a foundational source of cosmological information. Precision cosmological probes targeted primarily at investigations of dark energy require accurate theoretical determinations of the power…

Cosmology and Nongalactic Astrophysics · Physics 2010-08-26 Katrin Heitmann , David Higdon , Martin White , Salman Habib , Brian J. Williams , Christian Wagner

Current analyses of the Lyman-alpha forest assume that the primordial power spectrum of density perturbations obeys a simple power law, a strong theoretical assumption which should be tested. Employing a large suite of numerical simulations…

Cosmology and Nongalactic Astrophysics · Physics 2010-05-24 Simeon Bird

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

Modern sky surveys are returning precision measurements of cosmological statistics such as weak lensing shear correlations, the distribution of galaxies, and cluster abundance. To fully exploit these observations, theorists must provide…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Katrin Heitmann , Earl Lawrence , Juliana Kwan , Salman Habib , David Higdon

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

We outline the physical picture of the high-redshift Ly-alpha forest that has emerged from cosmological simulations, describe statistical characteristics of the forest that can be used to test theories of structure formation, present a…

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

In order to probe modifications of gravity at cosmological scales, one needs accurate theoretical predictions. N-body simulations are required to explore the non-linear regime of structure formation but are very time consuming. In this…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-24 Iñigo Sáez-Casares , Yann Rasera , Baojiu Li