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Damped Ly$\alpha$ systems provide possibly the most significant evidence for early structure formation, and thus a stringent constraint on the Cold + Hot Dark Matter (CHDM) cosmology. Using the numbers of halos in N-body simulations to…

Astrophysics · Physics 2009-09-25 Anatoly Klypin , Stefano Borgani , Jon Holtzman , Joel Primack

We present methods for interpolating between the 1-D flux power spectrum of the Lyman-$\alpha$ forest, as output by cosmological hydrodynamic simulations. Interpolation is necessary for cosmological parameter estimation due to the limited…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-25 Simeon Bird , Keir K. Rogers , Hiranya V. Peiris , Licia Verde , Andreu Font-Ribera , Andrew Pontzen

A novel machine learning algorithm is presented, serving as a data-driven turbulence modeling tool for Reynolds Averaged Navier-Stokes (RANS) simulations. This machine learning algorithm, called the Tensor Basis Random Forest (TBRF), is…

Fluid Dynamics · Physics 2020-04-20 Mikael L. A. Kaandorp , Richard P. Dwight

Machine learning has transformed domains like vision and translation, and is now increasingly used in science, where the correctness of such code is vital. Python is popular for machine learning, in part because of its wealth of machine…

Programming Languages · Computer Science 2018-05-11 Julian Dolby , Avraham Shinnar , Allison Allain , Jenna Reinen

The filamentary network of intergalactic medium (IGM) gas that gives origin to the Lyman-alpha forest in the spectra of distant quasars encodes information on the physics of structure formation and the early thermodynamics of diffuse…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-20 Bruno Villasenor , Brant Robertson , Piero Madau , Evan Schneider

We introduce PyMGal, a Python package for generating optical mock observations of galaxies from hydrodynamical simulations. PyMGal reads the properties of stellar particles from these simulations and generates spectral energy distributions…

Astrophysics of Galaxies · Physics 2025-07-02 Patrick Janulewicz , Weiguang Cui

Lyman limit and damped Lyman-alpha absorption systems probe the distribution of collapsed, cold gas at high redshift. Numerical simulations that incorporate gravity and gas dynamics can predict the abundance of such absorbers in…

Astrophysics · Physics 2009-10-28 Jeffrey P. Gardner , Neal Katz , Lars Hernquist , David H. Weinberg

We test and improve the numerical schemes in our smoothed particle hydrodynamics (SPH) code for cosmological simulations, including the pressure-entropy formulation (PESPH), a time-dependent artificial viscosity, a refined timestep…

We model the $\lya$ forest in a spatially flat, CDM model with $\Omega=0.4$, with an Eulerian hydrodynamic simulation, and find that the intergalactic, photoionized gas collapses into sheet-like and filamentary structures which produce…

Astrophysics · Physics 2009-10-28 Jordi Miralda-Escude , Renyue Cen , Jeremiah P. Ostriker , Michael Rauch

Hydrogen Ly-alpha is our primary emission-line window into high redshift galaxies. Surprisingly, despite an extensive literature, Ly-alpha radiative transfer in the most realistic case of a dusty, multi-phase medium has not received…

Astrophysics · Physics 2009-11-13 Matthew Hansen , S. Peng Oh

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 simulate the Lya forest in a standard CDM universe using a 2-level hierarchical grid code to evolve the dark and baryonic matter components self-consistently. We solve the time-dependent ionization equations for hydrogen and helium,…

Astrophysics · Physics 2009-10-28 Yu Zhang , Peter Anninos , Michael L. Norman , Avery Meiksin

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 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

We use cosmological smoothed-particle hydrodynamics (SPH) simulations of the Lambda cold dark matter (CDM) model to study the abundance of damped Lyman-alpha absorbers (DLAs) in the redshift range z=0-4.5. We compute the cumulative DLA…

Astrophysics · Physics 2008-11-26 Kentaro Nagamine , Volker Springel , Lars Hernquist

We determine the product of the expansion rate and angular-diameter distance at redshift $z=2.3$ from the anisotropy of Lyman-$\alpha$ (Ly$\alpha$) forest correlations measured by the Sloan Digital Sky Survey (SDSS). Our result is the most…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-21 Andrei Cuceu , Andreu Font-Ribera , Seshadri Nadathur , Benjamin Joachimi , Paul Martini

The intergalactic medium (IGM) acts like a calorimeter recording energy injection by cosmic structure formation, shocks and photoheating from stars and active galactic nuclei. It was recently proposed that spatially inhomogeneous…

Astrophysics of Galaxies · Physics 2022-03-14 A. Lamberts , E. Puchwein , C. Pfrommer , P. Chang , M. Shalaby , A. Broderick , P. Tiede , G. Rudie

Soft matter materials and polymers are widely used in the controlled delivery of drugs. Simulation and modeling provide insight at the atomic scale enabling a level of control unavailable to experiments. We present a workflow protocol for…

Soft Condensed Matter · Physics 2022-03-08 James P. Andrews , Estela Blaisten-Barojas

A thermal convection loop is a annular chamber filled with water, heated on the bottom half and cooled on the top half. With sufficiently large forcing of heat, the direction of fluid flow in the loop oscillates chaotically, dynamics…

Dynamical Systems · Mathematics 2016-06-24 Andrew J. Reagan , Yves Dubief , Peter Sheridan Dodds , Christopher M. Danforth

We present FORECAST, a new flexible and adaptable software package that performs forward modeling of the output of any cosmological hydrodynamical simulations to create a wide range of realistic synthetic astronomical images. With…