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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

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

We introduce a powerful semi-numeric modeling tool, 21cmFAST, designed to efficiently simulate the cosmological 21-cm signal. Our code generates 3D realizations of evolved density, ionization, peculiar velocity, and spin temperature fields,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Andrei Mesinger , Steven Furlanetto , Renyue Cen

We develop a numerical solver for radiative transfer problems based on the weighted essentially nonoscillatory (WENO) scheme modified with anti-diffusive flux corrections, in order to solve the temperature and ionization profiles around a…

Astrophysics · Physics 2008-11-26 Jing-Mei Qiu , Long-Long Feng , Chi-Wang Shu , Li-Zhi Fang

The morphology of the 21-cm signal emitted by the neutral hydrogen present in the intergalactic medium (IGM) during the Epoch of Reionization (EoR) depends both on the properties of the sources of ionizing radiation and on the underlying…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-04 Leon Noble , Mohd Kamran , Suman Majumdar , Chandra Shekhar Murmu , Raghunath Ghara , Garrelt Mellema , Ilian T. Iliev , Jonathan R. Pritchard

Spatial dependence in the statistics of redshifted 21cm fluctuations promises to provide the most powerful probe of the reionisation epoch. In this paper we consider the second and third moments of the redshifted 21cm intensity distribution…

Astrophysics · Physics 2015-06-24 Stuart Wyithe , Miguel Morales

The prospect of detecting the first galaxies by observing their impact on the intergalactic medium as they reionized it during the first billion years leads us to ask whether such indirect observations are capable of diagnosing which types…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Ilian T. Iliev , Garrelt Mellema , Paul R. Shapiro , Ue-Li Pen , Yi Mao , Jun Koda , Kyungjin Ahn

Most astrophysical plasmas entail a balance between ionization and recombination. We present new results from the powerful R-matrix method which yields in an ab initio manner: (I) self-consistent photoionization and recombination cross…

Astrophysics · Physics 2007-05-23 Sultana N. Nahar

The next generation 21 cm surveys open a new window onto the early stages of cosmic structure formation and provide new insights about the Epoch of Reionization (EoR). However, the non-Gaussian nature of the 21 cm signal along with the huge…

Cosmology and Nongalactic Astrophysics · Physics 2020-09-18 Héctor J. Hortúa , Luigi Malago , Riccardo Volpi

Randomization is currently a widely used approach in Sim2Real transfer for data-driven learning algorithms in robotics. Still, most Sim2Real studies report results for a specific randomization technique and often on a highly customized…

The process of reionization is now believed to have proceeded in an orchestrated manner beginning with UV photons emitted by high redshift galaxies containing a large fraction of Population III stars carving out ionised regions around them.…

Astrophysics · Physics 2008-11-26 Anze Slosar , Asantha Cooray , Joseph Silk

We use numerical simulations of hydrogen reionization by stellar sources in the context of LCDM cosmogonies to investigate the 21 (1+z) cm radio signal expected from the diffuse intergalactic medium (IGM) prior to the epoch of reionization…

Astrophysics · Physics 2009-07-09 B. Ciardi , P. Madau

Radiative cooling is an important ingredient in hydrodynamical models involving evolution of high temperature plasmas. Unfortunately, calculating an accurate cooling coefficient generally requires the solution of over a hundred differential…

Astrophysics · Physics 2009-11-06 Robert A. Benjamin , Bradford A. Benson , Donald P. Cox

We discuss the prospects for ``tomography'' of the intergalactic medium (IGM) at high redshifts using the 21 cm transition of neutral hydrogen. Existing observational constraints on the epoch of reionization imply a complex ionization…

Astrophysics · Physics 2009-11-10 Steven Furlanetto , Frank Briggs

Modern machine learning will allow for simulation-based inference from reionization-era 21cm observations at the Square Kilometre Array. Our framework combines a convolutional summary network and a conditional invertible network through a…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-16 Benedikt Schosser , Caroline Heneka , Tilman Plehn

We investigate whether the redshift evolution of the fixed-$k$ dimensionless 21 cm power spectrum, $\Delta^2_{21}(k, z)$, contains sufficient information to reconstruct reionization histories $x_{\mathrm{HI}}(z)$ with artificial neural…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-21 Yu-Le Wang , Hayato Shimabukuro

We explore the impact of reionization topology on 21-cm statistics. Four reionization models are presented which emulate large ionized bubbles around over-dense regions (21CMFAST/ global-inside- out), small ionized bubbles in over-dense…

Cosmology and Nongalactic Astrophysics · Physics 2014-08-15 Catherine A. Watkinson , Jonathan R. Pritchard

We predict the 21-cm global signal and power spectra during the Epoch of Reionisation using the MERAXES semi-analytic galaxy formation and reionisation model, updated to include X-ray heating and thermal evolution of the intergalactic…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-21 Sreedhar Balu , Bradley Greig , Yisheng Qiu , Chris Power , Yuxiang Qin , Simon Mutch , J. Stuart B. Wyithe

The epoch of reionization (EoR), marking the Universe's transition from a neutral to ionized state, represents a pivotal phase for understanding the formation of the first stars and galaxies. Intensity mapping of atomic and molecular lines,…

Astrophysics of Galaxies · Physics 2025-12-17 Anirban Roy , Anthony Pullen , Patrick C. Breysse , Rachel S. Somerville

We have developed a three-dimensional radiative transfer method designed specifically for use with parallel adaptive mesh refinement hydrodynamics codes. This new algorithm, which we call hybrid characteristics, introduces a novel form of…

Astrophysics · Physics 2009-11-11 Erik-Jan Rijkhorst , Tomasz Plewa , Anshu Dubey , Garrelt Mellema
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