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We model the distribution of neutral hydrogen (HI) in the post-reionization era and investigate its detectability in 21 cm intensity mapping with the future SKA radio telescope. We rely on high resolution hydrodynamical N-body simulations.…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Francisco Villaescusa-Navarro , Matteo Viel , Kanan K. Datta , T. Roy Choudhury

The observations of the redshifted 21-cm signal from neutral hydrogen are a promising probe for understanding the Cosmic Dawn and the Epoch of Reionisation (EoR). One of the primary obstacles to the statistical detection of the Cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-22 Eeshan Beohar , Abhirup Datta , Anshuman Tripathi , Samit Kumar Pal , Rashmi Sagar

Contemporary cosmic microwave background (CMB) experiments typically have observing bands covering the range 20 - 800 GHz. Certain science goals, including the detection of $\mu$-type distortions to the CMB spectrum and the characterization…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-07 David Zegeye , Thomas Crawford , Jens Chluba , Mathieu Remazeilles , Keith Grainge

The post-reionization $(z \le 6)$ neutral hydrogen (HI) 21-cm intensity mapping signal holds the potential to probe the large scale structures, study the expansion history and constrain various cosmological parameters. Here we apply the…

The redshifted 21~cm signal from neutral hydrogen (HI) is potentially a very powerful probe for cosmology, but a difficulty in its observation is that it is much weaker than foreground radiation from the Milky Way as well as extragalactic…

Cosmology and Nongalactic Astrophysics · Physics 2019-06-14 Shifan Zuo , Xuelei Chen , Reza Ansari , Youjun Lu

Neutral hydrogen (HI) $21$-cm intensity mapping (IM) is a promising probe of the large-scale structures in the Universe. However, a few orders of magnitude brighter foregrounds obscure the IM signal. Here we use the Tapered Gridded…

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

One of the main challenges for future 21 cm observations is to remove foregrounds which are several orders of magnitude more intense than the HI signal. We propose a new technique for removing foregrounds of the redshifted 21 cm…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Jungyeon Cho , A. Lazarian , P. Timbie

The Square Kilometre Array (SKA) will conduct the biggest spectroscopic galaxy survey ever, by detecting the 21cm emission line of neutral hydrogen (HI) from around a billion galaxies over 3/4 of the sky, out to a redshift of z~2. This will…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-08 S. Yahya , P. Bull , M. G. Santos , M. Silva , R. Maartens , P. Okouma , B. Bassett

A number of current and future experiments aim to detect the reionization of neutral hydrogen by the first stars and galaxies in the Universe via the redshifted 21cm line. Using the \textsc{BlueTides} simulation, we investigate the…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-20 James E Davies , Rupert A. Croft , Tiziana Di-Matteo , Bradley Greig , Yu Feng , Stuart Wyithe

Observation of multifrequency angular power spectrum of the redshifted 21-cm brightness temperature fluctuation from the neutral hydrogen holds the key to understand the structure formation and its evolution during the reionization and…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-28 Saikat Gayen , Jais Kumar , Prasun Dutta , Khandakar Md Asif Elahi , Samir Choudhuri , Nirupam Roy

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

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

We introduce a new Bayesian HI spectral line fitting technique capable of obtaining spectroscopic redshifts for millions of galaxies in radio surveys with the Square Kilometere Array (SKA). This technique is especially well-suited to the…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-28 Ian Harrison , Michelle Lochner , Michael L. Brown

\textsc{Hi} intensity mapping will provide maps of the large-scale distribution of neutral hydrogen (\textsc{Hi}) in the universe. These are prime candidates to be used to constrain primordial non-Gaussianity using the Large Scale Structure…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-03 José Fonseca , Michele Liguori

Mapping the distribution of neutral atomic hydrogen (HI) in the Universe through its 21 cm emission line provides a powerful cosmological probe to map the large-scale structures and shed light on various cosmological phenomena. The Baryon…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-20 Albin Joseph , Rajib Saha

The highly redshifted 21 cm line of neutral hydrogen has become recognized as a unique probe of cosmology from relatively low redshifts (z ~ 1) up through the Epoch of Reionization (z ~ 8) and even beyond. To date, most work has focused on…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-23 Jonathan C. Pober

The bispectrum is a 3-point statistic with the potential to provide additional information beyond power spectra analyses of survey datasets. Radio telescopes which broadly survey the 21cm emission from neutral hydrogen (HI) are a promising…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-11 Steven Cunnington , Catherine Watkinson , Alkistis Pourtsidou

We report the first direct detection of the cosmological power spectrum using the intensity signal from 21-cm emission of neutral hydrogen (HI), derived from interferometric observations with the L-band receivers of the new MeerKAT radio…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-31 Sourabh Paul , Mario G. Santos , Zhaoting Chen , Laura Wolz