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We seek to remove foreground contaminants from 21cm intensity mapping observations. We demonstrate that a deep convolutional neural network (CNN) with a UNet architecture and three-dimensional convolutions, trained on simulated…

The Largest Cluster Statistics\,(LCS) analysis of the redshifted 21\,cm maps has been demonstrated to be an efficient and robust method for following the time evolution of the largest ionized regions\,(LIRs) during the Epoch of…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-28 Samit Kumar Pal , Saswata Dasgupta , Abhirup Datta , Suman Majumdar , Satadru Bag , Prakash Sarkar

The Square Kilometre Array (SKA) will offer an unprecedented view onto the early Universe, using interferometric observations of the redshifted 21cm line. The 21cm line probes the thermal and ionization state of the cosmic gas, which is…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-14 Andrei Mesinger , Andrea Ferrara , Bradley Greig , Ilian Iliev , Garrelt Mellema , Jonathan Pritchard , Mario G. Santos

In this paper, we propose a novel method to recover the 21cm global signal from the 21cm power spectrum using artificial neural networks (ANNs). The 21cm global signal is crucial for understanding cosmic evolution from the Dark Ages through…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-09 Hayato Shimabukuro

The epoch of reionization (EoR) sets a fundamental benchmark in cosmic structure formation, corresponding to the formation of the first luminous objects that act to ionize the neutral intergalactic medium (IGM). Recent observations at…

Astrophysics · Physics 2009-11-10 C. Carilli , S. Furlanetto , F. Briggs , M. Jarvis , S. Rawlings , H. Falcke

The exceptional sensitivity of the SKA will allow observations of the Cosmic Dawn and Epoch of Reionization (CD/EoR) in unprecedented detail, both spectrally and spatially. This wealth of information is buried under Galactic and…

Instrumentation and Methods for Astrophysics · Physics 2015-01-20 Emma Chapman , Anna Bonaldi , Geraint Harker , Vibor Jelić , Filipe B. Abdalla , Gianni Bernardi , Jérôme Bobin , Fred Dulwich , Benjamin Mort , Mario Santos , Jean-Luc Starck

Strong gravitational lensing provides some of the deepest views of the Universe, enabling studies of high-redshift galaxies only possible with next-generation facilities without the lensing phenomenon. To date, 21 cm radio emission from…

Astrophysics of Galaxies · Physics 2015-08-06 R. P. Deane , D. Obreschkow , I. Heywood

The Cosmic Dawn was marked by the formation of the first stars, and preceded the Epoch of Reionization (EoR), when the Universe underwent a fundamental transformation caused by the radiation from these first stars and galaxies.…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-04 Oscar Sage David O'Hara , Fred Dulwich , Eloy de Lera Acedo , Jiten Dhandha , Thomas Gessey-Jones , Dominic Anstey , Anastasia Fialkov

Cross-correlations between 21cm observations and galaxy surveys provide a powerful probe of reionization by reducing foreground sensitivity while linking ionization morphology to galaxies. We quantify the constraining power of 21cm-Galaxy…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-27 Yannic Pietschke , Anne Hutter , Caroline Heneka

The ability of the future low frequency component of the Square Kilometre Array radio telescope (SKA-Low) to produce tomographic images of the redshifted 21-cm signal will enable direct studies of the evolution of the sizes and shapes of…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-06 Sambit K. Giri , Garrelt Mellema , Raghunath Ghara

The upcoming Square Kilometre Array Observatory (SKAO) will produce images of neutral hydrogen distribution during the epoch of reionization by observing the corresponding 21-cm signal. However, the 21-cm signal will be subject to…

Instrumentation and Methods for Astrophysics · Physics 2024-02-29 Michele Bianco , Sambit. K. Giri , David Prelogović , Tianyue Chen , Florent G. Mertens , Emma Tolley , Andrei Mesinger , Jean-Paul Kneib

Upcoming measurements of the high-redshift 21 cm signal from the Epoch of Reionization (EoR) are a promising probe of the astrophysics of the first galaxies and of cosmological parameters. In particular, the optical depth $\tau$ to the last…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-29 Tashalee S. Billings , Paul La Plante , James E. Aguirre

Low-frequency radio observations of neutral hydrogen during and before the epoch of cosmic reionization will provide ~ 1000 quasi-independent source planes, each of precisely known redshift, if a resolution of ~1 arcminutes or better can be…

Astrophysics · Physics 2017-03-15 R. Benton Metcalf , S. D. M. White

We analyse the evolution of the largest ionized region using the topological and morphological evolution of the redshifted 21-cm signal coming from the neutral hydrogen distribution during the different stages of reionization. For this…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-12 Saswata Dasgupta , Samit Kumar Pal , Satadru Bag , Sohini Dutta , Suman Majumdar , Abhirup Datta , Aadarsh Pathak , Mohd Kamran , Rajesh Mondal , Prakash Sarkar

Neutral hydrogen (H$_{\rm I}$) intensity mapping is capable of measuring redshift evolution of H$_{\rm I}$ density parameter $\Omega_{\rm H_{\rm I}}$, which is an important parameter to understand structure formation in the…

Cosmology and Nongalactic Astrophysics · Physics 2020-09-28 Shoichiro Tanaka , Shintaro Yoshiura , Kenji Kubota , Keitaro Takahashi , Atsushi J. Nishizawa , Naoshi Sugiyama

Within the next few years, the Square Kilometer Array (SKA) or one of its pathfinders will hopefully provide a detection of the 21-cm signal fluctuations from the Epoch of Reionization (EoR). Then, the main goal will be to accurately…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-25 Aristide Doussot , Evan Eames , Benoit Semelin

The Epoch of Reionization (EoR) is a unique phase in cosmic history, marked by the ionization of neutral hydrogen by the first luminous sources. The global neutral hydrogen fraction (x_HI) is a key observable for probing this era. This…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-18 Jiajun Zhang , Huanyuan Shan

Measurements of the 21cm line emission by residual cosmic hydrogen after reionization can be used to trace the power spectrum of density perturbations through a significant fraction of the observable volume of the Universe. We show that a…

Astrophysics · Physics 2009-06-23 Abraham Loeb , Stuart Wyithe

We argue that the Square Kilometre Array has the potential to make both redshift (HI) surveys and radio continuum surveys that will revolutionize cosmological studies, provided that it has sufficient instantaneous field-of-view that these…

Astrophysics · Physics 2009-11-10 Chris Blake , Filipe Abdalla , Sarah Bridle , Steve Rawlings

21-cm emission from neutral hydrogen during and before the epoch of cosmic reionisation is gravitationally lensed by material at all lower redshifts. Low-frequency radio observations of this emission can be used to reconstruct the projected…

Astrophysics · Physics 2009-06-25 Stefan Hilbert , R. Benton Metcalf , S. D. M. White