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Recently the numerical simulations of the process of reionization of the universe at z>6 have made a qualitative leap forward, reaching sufficient sizes and dynamic range to determine the characteristic scales of this process. This allowed…

The characterisation of the atomic and molecular hydrogen content of high-redshift galaxies is a major observational challenge that will be addressed over the coming years with a new generation of radio telescopes. We investigate this…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-13 Alan R. Duffy , Scott T. Kay , Richard A. Battye , C. M. Booth , Claudio Dalla Vecchia , Joop Schaye

Aiming to correctly restore the redshifted 21 cm signals emitted by the neutral hydrogen during the cosmic reionization processes, we re-examine the separation approaches based on the quadratic polynomial fitting technique in frequency…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Jingying Wang , Haiguang Xu , Tao An , Junhua Gu , Xueying Guo , Weitian Li , Yu Wang , Chengze Liu , Olivier Martineau-Huynh , Xiang-Ping Wu

In a semi-numerical model of reionization, the evolution of ionization fraction is simulated approximately by the ionizing photon to baryon ratio criterion. In this paper we incorporate a semi-analytical model of galaxy formation based on…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Jie Zhou , Qi Guo , Gaochao Liu , Bin Yue , Yidong Xu , Xuelei Chen

We introduce a new suite of radiation-hydrodynamical simulations of galaxy formation and reionization called Aurora. The Aurora simulations make use of a spatially adaptive radiative transfer technique that lets us accurately capture the…

Astrophysics of Galaxies · Physics 2017-01-18 Andreas H. Pawlik , Alireza Rahmati , Joop Schaye , Myoungwon Jeon , Claudio Dalla Vecchia

We consider the degree to which "21 cm tomography" of the high-redshift Universe can distinguish different ionization histories. Using a new analytic model for the size distribution of HII regions that associates these ionized bubbles with…

Astrophysics · Physics 2009-09-29 Steven Furlanetto , Matias Zaldarriaga , Lars Hernquist

In the absence of complex astrophysical processes that characterize the reionization era, the 21-cm emission from neutral hydrogen (HI) in the post-reionization epoch is believed to be an excellent tracer of the underlying dark matter…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Tapomoy Guha Sarkar , Sourav Mitra , Suman Majumdar , Tirthankar Roy Choudhury

The reionization of the second electron of helium shapes the physical state of intergalactic gas at redshifts between 2 < z < 5. Because performing full in situ radiative transfer in hydrodynamic simulations is computationally expensive for…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-22 Phoebe Upton Sanderbeck , Simeon Bird

We combine high resolution hydrodynamical simulations with an intermediate resolution, dark matter only simulation and an analytical model for the growth of ionized regions to estimate the large scale distribution and redshift evolution of…

Cosmology and Nongalactic Astrophysics · Physics 2015-07-15 Tirthankar Roy Choudhury , Ewald Puchwein , Martin G. Haehnelt , James S. Bolton

We use a set of cosmological simulations combined with radiative transfer calculations to investigate the distribution of neutral hydrogen in the post-reionization Universe. We assess the contributions from the metagalactic ionizing…

Cosmology and Nongalactic Astrophysics · Physics 2013-08-27 Alireza Rahmati , Andreas H. Pawlik , Milan Raičević , Joop Schaye

We describe an approach for incorporating radiative transfer into 3D hydrodynamic cosmological simulations. The method, while approximate, allows for a self-consistent treatment of self-shielding and shadowing, diffuse and point sources of…

Astrophysics · Physics 2007-05-23 Michael L. Norman , Paschalis Paschos , Tom Abel

We use cosmological simulations of reionization to predict the effect of large HII regions around individual high-redshift quasars on the possible signal from the redshifted 21cm line of neutral hydrogen in the pre-reionization era. We show…

Astrophysics · Physics 2009-11-10 Katharina Kohler , Nickolay Y. Gnedin , Jordi Miralda-Escude , Peter A. Shaver

Modelling reionization often requires significant assumptions about the properties of ionizing sources. Here, we infer the total output of hydrogen-ionizing photons (the ionizing emissivity, $\dot{N}_\textrm{ion}$) at $z=4-14$ from current…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-12 Charlotte A. Mason , Rohan P. Naidu , Sandro Tacchella , Joel Leja

Semi-analytic models are a valuable tool to study the first stars and galaxies. Their numerical efficiency makes it possible to survey broad regions of astrophysical parameter space across large volumes and redshift ranges. Following…

Astrophysics of Galaxies · Physics 2025-08-08 Thomas Behling , Ryan Hazlett , Mihir Kulkarni , Eli Visbal

We present semi-analytic models of the epoch of reionization focusing on the differences between continuous and bursty star formation (SF). Our model utilizes physically motivated analytic fits to 1D radiative transfer simulations of HII…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-17 Blake Hartley , Massimo Ricotti

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 extend our super-resolution and emulation framework for cosmological dark matter simulations to include hydrodynamics. We present a two-stage deep learning model to emulate high-resolution (HR-HydroSim) baryonic fields from…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-23 Fatemeh Hafezianzadeh , Xiaowen Zhang , Yueying Ni , Rupert A. C. Croft , Tiziana DiMatteo , Mahdi Qezlou , Simeon Bird

We introduce the ASTRID simulation, a large-scale cosmological hydrodynamic simulation in a $250$ Mpc/h box with $2\times 5500^3$ particles. ASTRID contains a large number of high redshift galaxies, which can be compared to future survey…

Astrophysics of Galaxies · Physics 2022-03-24 Simeon Bird , Yueying Ni , Tiziana Di Matteo , Rupert Croft , Yu Feng , Nianyi Chen

I use cosmological simulations that incorporate a physically motivated approximation to three-dimensional radiative transfer that recovers correct asymptotic ionization front propagation speeds for some cosmologically relevant density…

Astrophysics · Physics 2009-10-31 Nickolay Y. Gnedin

We extend 21CMMC, a Monte Carlo Markov Chain sampler of 3D reionisation simulations, to perform parameter estimation directly on 3D light-cones of the cosmic 21cm signal. This brings theoretical analysis closer to the tomographic 21-cm…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-11 Bradley Greig , Andrei Mesinger