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Hydrodynamical simulations of galaxy formation such as the Illustris simulations have progressed to a state where they approximately reproduce the observed stellar mass function from high to low redshift. This in principle allows…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-01 Andreas Bauer , Volker Springel , Mark Vogelsberger , Shy Genel , Paul Torrey , Debora Sijacki , Dylan Nelson , Lars Hernquist

We present an efficient method to generate large simulations of the Epoch of Reionization (EoR) without the need for a full 3-dimensional radiative transfer code. Large dark-matter-only simulations are post-processed to produce maps of the…

We present a new suite of late-end reionization simulations performed with ATON-HE, a revised version of the GPU-based radiative transfer code ATON that includes helium. The simulations are able to reproduce the Ly$\alpha$ flux distribution…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-12 Shikhar Asthana , Martin G. Haehnelt , Girish Kulkarni , Dominique Aubert , James S. Bolton , Laura C. Keating

Radiation hydrodynamical transport of ionization fronts in the next generation of cosmological reionization simulations holds the promise of predicting UV escape fractions from first principles as well as investigating the role of…

Astrophysics · Physics 2009-11-11 Daniel J. Whalen , Michael L. Norman

Large-scale reionization simulations are described which combine the results of cosmological N-body simulations that model the evolving density and velocity fields and identify the galactic halo sources, with ray-tracing radiative transfer…

Lyman-alpha forest data probing the post-reionization Universe shows surprisingly large opacity fluctuations over rather large ($\ge$50 comoving Mpc/h) spatial scales. We model these fluctuations using a hybrid approach utilizing the large…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-21 Jonathan Chardin , Ewald Puchwein , Martin G. Haehnelt

A comprehensive description of molecular electron transfer reactions is essential for our understanding of fundamental phenomena in bio-energetics and molecular electronics. Experimental studies of molecular systems in condensed-phase…

Quantum Physics · Physics 2021-02-04 Frank Schlawin , Manuel Gessner , Andreas Buchleitner , Tobias Schaetz , Spiros S Skourtis

Quasar absorption spectra measurements suggest that reionization proceeded rapidly, ended late at $z \sim 5.5$, and was followed by a flat ionizing background evolution. Simulations that reproduce this behavior often rely on a fine tuned…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-20 Christopher Cain , Anson D'Aloisio , Garett Lopez , Nakul Gangolli , Joshua T. Roth

We present a computationally efficient and fast semi-numerical technique for simulating the Lyman-$\alpha$ (Ly$\alpha$) absorption optical depth in presence of neutral hydrogen "islands" left over from reionization at redshifts $5 \lesssim…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-20 T. Roy Choudhury , Aseem Paranjape , Sarah E. I. Bosman

Common moment-based radiative transfer methods, such as flux-limited diffusion (FLD) and the M1 closure, suffer from artificial interactions between crossing beams. In protoplanetary disks, this leads to an overestimation of the midplane…

Instrumentation and Methods for Astrophysics · Physics 2025-09-30 David Melon Fuksman , Mario Flock , Hubert Klahr , Giancarlo Mattia , Dhruv Muley

Radiative transfer calculations are essential for modeling planetary atmospheres. However, standard methods are computationally demanding and impose accuracy-speed trade-offs. High computational costs force numerical simplifications in…

Earth and Planetary Astrophysics · Physics 2025-11-03 Isaac Malsky , Tiffany Kataria , Natasha E. Batalha , Matthew Graham

Favorably scaling numerical time-dependent many-electron techniques such as time-dependent density functional theory (TDDFT) with adiabatic exchange-correlation potentials typically fail in capturing highly correlated electron dynamics. We…

Atomic Physics · Physics 2013-11-25 M. Brics , D. Bauer

Constraints on the ionization structure of the Intergalactic Medium are derived as directly imposed by observations in conjunction with the results of numerical simulations for structure formation. Under the assumption that the population…

Astrophysics · Physics 2009-11-10 A. Meiksin

Predicting the 21cm signal from the epoch of reionization and cosmic dawn is a complex and challenging task. Various simplifying assumptions have been applied over the last decades to make the modeling more affordable. In this paper, we…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-25 Timothée Schaeffer , Sambit K. Giri , Aurel Schneider

Lyman-limit absorption systems can play many important roles during and after cosmological reionization. Unfortunately, due to the prohibitively large dynamic range required, it is impossible to self-consistently include these systems in…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Daniela Crociani , Andrei Mesinger , Lauro Moscardini , Steven Furlanetto

We have developed an algorithm for transferring radiation in three-dimensional space. The algorithm computes radiation source and sink terms using the Fast Fourier Transform (FFT) method, based on a formulation in which the integral of any…

Astrophysics · Physics 2009-11-07 Renyue Cen

In a recent article the authors showed that the radiative Transfer equations with multiple frequencies and scattering can be formulated as a nonlinear integral system. In the present article, the formulation is extended to handle reflective…

Numerical Analysis · Mathematics 2023-06-12 Olivier Pironneau , Pierre-Henri Tournier

The reduced speed of light approximation is used in a variety of simulations of the epoch of reionization and galaxy formation. Its popularity stems from its ability to drastically reduce the computing cost of a simulation, by allowing the…

Cosmology and Nongalactic Astrophysics · Physics 2019-06-19 P. Ocvirk , D. Aubert , J. Chardin , N. Deparis , J. Lewis

We present a new radiative transfer method (SPH-M1RT) that is coupled dynamically with smoothed particle hydrodynamics (SPH). We implement it in the (task-based parallel) SWIFT galaxy simulation code but it can be straightforwardly…

Instrumentation and Methods for Astrophysics · Physics 2021-07-06 T. K. Chan , Tom Theuns , Richard Bower , Carlos Frenk

(Abridged) We describe a new algorithm for solving the coupled frequency-integrated transfer equation and the equations of magnetohydrodynamics when the light-crossing time is only marginally shorter than dynamical timescales. The transfer…

Instrumentation and Methods for Astrophysics · Physics 2014-06-24 Yan-Fei Jiang , James M. Stone , Shane W. Davis