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During the epoch of reionization (EoR), the 21-cm signal allows direct observation of the neutral hydrogen (HI) in the intergalactic medium (IGM). In the post-reionization era, this signal instead probes HI in galaxies, which traces the…

Cosmology and Nongalactic Astrophysics · Physics 2024-08-20 Sambit K. Giri , Michele Bianco , Timothée Schaeffer , Ilian T. Iliev , Garrelt Mellema , Aurel Schneider

We present a sophisticated statistical point-source foreground model for low-frequency radio Epoch of Reionization (EoR) experiments using the 21 cm neutral hydrogen emission line. Motivated by our understanding of the low-frequency radio…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-16 Steven G. Murray , Cathryn M. Trott , Christopher H. Jordan

We use a set of semi-numerical simulations based on Zel'dovich approximation, friends-of-friends algorithm and excursion set formalism to generate reionization maps of high dynamic range with a range of assumptions regarding the…

Astrophysics · Physics 2009-11-13 T. Roy Choudhury , M. G. Haehnelt , J. Regan

We have developed a modular semi-numerical code that computes the time and spatially dependent ionization of neutral hydrogen (HI), neutral (HeI) and singly ionized helium (HeII) in the intergalactic medium (IGM). The model accounts for…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-02 Anne Hutter

We present new calculations of the inhomogeneous process of cosmological reionization by carefully following the radiative transfer in pre-computed hydrodynamical simulations of galaxy formation. These new computations represent an…

Astrophysics · Physics 2009-11-07 Alexei O. Razoumov , Michael L. Norman , Tom Abel , Douglas Scott

High-redshift 21-cm observations will provide crucial insights into the physical processes of the Epoch of Reionization. Next-generation interferometers such as the Square Kilometer Array will have enough sensitivity to directly image the…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-27 Simon Gazagnes , Léon V. E. Koopmans , Michael H. F. Wilkinson

Detecting redshifted 21cm emission from neutral hydrogen in the early Universe promises to give direct constraints on the epoch of reionization (EoR). It will, though, be very challenging to extract the cosmological signal (CS) from…

In the Simulations and Constructions of the Reionization of Cosmic Hydrogen (SCORCH) project, we compare analytical models of the hydrogen ionization fraction with radiation-hydrodynamic simulations. We derive analytical models of the…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-28 Nianyi Chen , Aristide Doussot , Hy Trac , Renyue Cen

We describe a new methodology to analyze the reionization process in numerical simulations: the chronology and the geometry of reionization is investigated by means of merger histories of individual HII regions. From the merger tree of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Jonathan Chardin , Dominique Aubert , Pierre Ocvirk

In this work we present a new hybrid method to simulate the thermal effects of the reionization in cosmological hydrodynamical simulations. The method improves upon the standard approach used in simulations of the intergalactic medium (IGM)…

Cosmology and Nongalactic Astrophysics · Physics 2019-06-11 Jose Oñorbe , F. B. Davies , Z. Lukić , J. F. Hennawi , D. Sorini

We use the photon flux and absorption tracer algorithm presented in Katz et al.~2018, to characterise the contribution of haloes of different mass and stars of different age and metallicity to the reionization of the Universe. We employ a…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-05 Harley Katz , Taysun Kimm , Martin G. Haehnelt , Debora Sijacki , Joakim Rosdahl , Jeremy Blaizot

Cosmic reionization was driven by the imbalance between early sources and sinks of ionizing radiation, both of which were dominated by small-scale structure and are thus usually treated in cosmological reionization simulations by subgrid…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-05 Yi Mao , Jun Koda , Paul R. Shapiro , Ilian T. Iliev , Garrelt Mellema , Hyunbae Park , Kyungjin Ahn , Michele Bianco

The measurements of the 21-cm brightness temperature fluctuations from the neutral hydrogen at the Epoch of Reionization (EoR) should inaugurate the next generation of cosmological observables. In this respect, many works have concentrated…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-10 Sebastien Clesse , Laura Lopez-Honorez , Christophe Ringeval , Hiroyuki Tashiro , Michel H. G. Tytgat

We present a method to construct semi-numerical ``simulations'', which can efficiently generate realizations of halo distributions and ionization maps at high redshifts. Our procedure combines an excursion-set approach with first-order…

Astrophysics · Physics 2009-11-13 Andrei Mesinger , Steven Furlanetto

Interpreting 21cm measurements from current and upcoming experiments like HERA and the SKA will provide new scientific insights and exciting implications for astrophysics and cosmology regarding the Epoch of Reionization (EoR). Several…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-03 Yihao Zhou , Paul La Plante

Theoretically self-consistent calculations for photoionization and (e + ion) recombination are described. An identical eigenfunction expansion for the ion is employed in coupled channel calculations for both processes, thus ensuring…

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

We explore the ability of measurements of the 21-cm power spectrum during reionization to enable the simultaneous reconstruction of the reionization history and the properties of the ionizing sources. For various sets of simulated 21-cm…

Astrophysics · Physics 2015-05-13 Rennan Barkana

We present predictions for two statistical measures of the hydrogen reionization process at high redshift. The first statistic is the number of neutral segments identified in spectra of high redshift QSOs as a function of their length. The…

Astrophysics · Physics 2009-11-07 Adi Nusser , Andrew Benson , Naoshi Sugiyama , Cedric Lacey

Density inhomogeneity in the intergalactic medium (IGM) can boost the recombination rate of ionized gas substantially, affecting the growth of HII regions during reionization. Previous attempts to quantify this effect typically failed to…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-09 Hyunbae Park , Paul R. Shapiro , Jun-hwan Choi , Naoki Yoshida , Shingo Hirano , Kyungjin Ahn

An ionization front expanding into a neutral medium can be slowed-down significantly by recombinations. In cosmological numerical simulations the recombination rate is often computed using a 'clumping factor', that takes into account that…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-17 Milan Raičević , Tom Theuns