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Constraining the timescale and manner in which the Epoch of Reionization (EoR) occurred is a major JWST science goal. However, any constraints on the stellar or ionizing parameters (xi ion) of galaxies in the EoR must contend with biases…

Early results from the JWST observations have reported a surprisingly high number of UV-bright galaxies at $z \geq 10$, which appears to challenge the theoretical predictions from standard galaxy formation models in the $\Lambda$CDM…

Astrophysics of Galaxies · Physics 2024-07-30 Anirban Chakraborty , Tirthankar Roy Choudhury

We present the first detailed structure formation and radiative transfer simulations of the reionization history of our cosmic neighbourhood. To this end, we follow the formation of the Local Group of galaxies and nearby clusters by means…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Ilian T. Iliev , Ben Moore , Stefan Gottloeber , Gustavo Yepes , Yehuda Hoffman , Garrelt Mellema

An ionization front (I-front) that propagates through an inhomogeneous medium is slowed down by self-shielding and recombinations. We perform cosmological radiation hydrodynamics simulations of the I-front propagation during the epoch of…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-12 Tsang Keung Chan , Alejandro Benitez-Llambay , Tom Theuns , Carlos Frenk , Richard Bower

The final stages of cosmic reionisation (EndEoR) are expected to be strongly regulated by the residual neutral hydrogen in the already ionised regions of the Universe. Its presence limits the mean distance that ionising photons can travel…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-19 Ivelin Georgiev , Garrelt Mellema , Sambit K. Giri

Experiments designed to measure the redshifted 21~cm line from the Epoch of Reionization (EoR) are challenged by strong astrophysical foreground contamination, ionospheric distortions, complex instrumental response and other different types…

We apply Bayesian statistics to perform model selection on different reionisation scenarios via the Multinest algorithm. Initially, we recover the results shown by 21CMMC for the parameter estimation of 21cmFAST models. We proceed to test…

Instrumentation and Methods for Astrophysics · Physics 2019-05-15 T. Binnie , J. R. Pritchard

A unified scheme using the R-matrix method has been developed for electron-ion recombination subsuming heretofore separate treatments of radiative and dielectronic recombination (RR and DR). The ab initio coupled channel approach unifies…

Astrophysics · Physics 2009-11-10 Sultana N. Nahar , Anil K. Pradhan

In this paper we investigate how the Reionization process is affected by early galaxy formation in different cosmological scenarios. We use a semi-analytic model with suppressed initial power spectra to obtain the UV Luminosity Function in…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-12 Massimiliano Romanello , Nicola Menci , Marco Castellano

The Lyman alpha (Lya) forest in the spectra of z>5 quasars provides a powerful probe of the late stages of the Epoch of Reionization (EoR). With the recent advent of exquisite datasets such as XQR-30, many models have struggled to reproduce…

Many observations indicate the occurrence of ionised gas in the distant halos of galaxies (including our own). Since photoionisation by stars (mainly O stars, young or evolved low-mass stars depending on the kind of galaxy) does not seem to…

Astrophysics · Physics 2009-10-30 G. T. Birk , H. Lesch , T. Neukirch

We use numerical simulations of cosmic reionization and radiative processes related to the HI 21 cm emission line to produce synthetic radio maps as seen by next generation radio telescopes that will operate at low radio frequencies (e.g.…

Astrophysics · Physics 2009-11-11 M. Valdes , B. Ciardi , A. Ferrara , M. Johnston-Hollitt , H. Rottgering

Reionization is a process whereby hydrogen (and helium) in the Universe is ionized by the radiation from first luminous sources. Theoretically, the importance of the reionization lies in its close coupling with the formation of first cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-18 T. Roy Choudhury

Understanding the epoch of reionization and the properties of the first galaxies represents an important goal for modern cosmology. The structure of reionization, and hence the observed power spectrum of redshifted 21cm fluctuations are…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Han-Seek Kim , J. Stuart B. Wyithe , Sudhir Raskutti , C. G. Lacey , J. C. Helly

Recent JWST observations at $z > 6$ may imply galactic ionizing photon production above prior expectations. Under observationally motivated assumptions about escape fractions, these suggest a $z \sim 8-9$ end to reionization, in tension…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-15 Christopher Cain , Garett Lopez , Anson D'Aloisio , Julian B. Munoz , Rolf A. Jansen , Rogier A. Windhorst , Nakul Gangolli

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…

We have developed an improved recombination calculation of H, HeI, and HeII in the early Universe which involves a line-by-line treatment of each atomic level. We find two major differences compared with previous calculations. Firstly, the…

Astrophysics · Physics 2009-09-25 Sara Seager , Dimitar D. Sasselov , Douglas Scott

The evolution of topology and morphology of ionized or neutral hydrogen during different stages of the Epoch of Reionization (EoR) have the potential to provide us a great amount of information about the properties of the ionizing sources…

Cosmology and Nongalactic Astrophysics · Physics 2022-11-23 Aadarsh Pathak , Satadru Bag , Saswata Dasgupta , Suman Majumdar , Rajesh Mondal , Mohd Kamran , Prakash Sarkar

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

Simulating the distribution of cosmological neutral hydrogen (HI) during the epoch of reionization requires a high dynamic range and is hence computationally expensive. The size of the simulation is dictated by the largest scales one aims…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-24 Ankur Barsode , Tirthankar Roy Choudhury