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The cosmic radio-frequency spectrum is expected to show a strong absorption signal corresponding to the 21-centimetre-wavelength transition of atomic hydrogen around redshift 20, which arises from Lyman-alpha radiation from some of the…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-20 Rennan Barkana

The 21-cm signal from the epoch of cosmic dawn prior to reionization consists of a promising observable to gain new insights into the dark matter (DM) sector. In this paper, we investigate its potential to constrain mixed (cold + non-cold)…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-04 Sambit K. Giri , Aurel Schneider

Separating the cosmological redshifted 21-cm signal from foregrounds is a major challenge. We present the cross-correlation of the redshifted 21-cm emission from neutral hydrogen (HI) in the post-reionization era with the Ly-alpha forest as…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Tapomoy Guha Sarkar , Somnath Bharadwaj , Tirthankar Roy Choudhury , Kanan Datta

Predicting the 21cm signal from the epoch of reionization and cosmic dawn is a complex and challenging task. Various simplifying assumptions have been applied over the last decades to make the modeling more affordable. In this paper, we…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-25 Timothée Schaeffer , Sambit K. Giri , Aurel Schneider

The redshifted 21-cm line of hydrogen holds great potential for the study of cosmology, as it can probe otherwise unobservable cosmic epochs. In particular, measurements of the 21-cm power spectrum during cosmic dawn---the era when the…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-27 Julian B. Muñoz

Observations of the redshifted 21-cm hyperfine line of neutral hydrogen from early phases of the Universe such as Cosmic Dawn and the Epoch of Reionization promise to open a new window onto the early formation of stars and galaxies. We…

The redshifted 21-cm emission by neutral hydrogen offers a unique tool for mapping structure formation in the early universe in three dimensions. Here we provide the first detailed calculation of the 21-cm emission signal during and after…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Anastasia Fialkov , Abraham Loeb

We present the evolution of the 21-cm signal from cosmic dawn and the epoch of reionization (EoR) in an upgraded model including three subtle effects of Ly-a radiation: Ly-a heating, CMB heating (mediated by Ly-a photons), and multiple…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-18 Itamar Reis , Anastasia Fialkov , Rennan Barkana

The sky-averaged (global) 21-cm signal is a powerful probe of the intergalactic medium (IGM) prior to the completion of reionization. However, it has so far been unclear that even in the best case scenario, in which the signal is accurately…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Jordan Mirocha , Geraint J. A. Harker , Jack O. Burns

The 21-cm signal from the epoch of cosmic dawn ($z \sim 10-30$) offers a powerful probe of new physics. One standard mechanism for constraining decaying dark matter from 21-cm observations relies on heating of the intergalactic medium by…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-31 Dominic Agius , Tracy Robyn Slatyer

The Lyman-$\alpha$ photons couple the spin temperature of neutral hydrogen (HI) to the kinetic temperature during the era of cosmic dawn. During this process, they also exchange energy with the medium, heating and cooling the HI. In…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-25 Janakee Raste , Shiv K. Sethi

The 21-cm signal from neutral hydrogen serves as a critical tool for unraveling the astrophysical processes that shaped cosmic dawn and the epoch of reionization. We explore the usually overlooked impact of re-scattering of 21-cm photons…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-03 Sudipta Sikder , Rennan Barkana , Anastasia Fialkov

Intensity mapping of 21-cm line by several radio telescope experiments will probe the large-scale structure of the Universe in the post-reionization epoch. It requires a theoretical framework of neutral hydrogen (HI) clustering, such as…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-18 Rika Ando , Atsushi J Nishizawa , Shimizu Ikkoh , Kentaro Nagamine

The properties of the first galaxies, expected to drive the Cosmic Dawn (CD) and the Epoch of Reionization (EoR), are encoded in the 3D structure of the cosmic 21-cm signal. Parameter inference from upcoming 21-cm observations promises to…

Astrophysics of Galaxies · Physics 2019-01-24 Jaehong Park , Andrei Mesinger , Bradley Greig , Nicolas Gillet

The upcoming radio interferometer Square Kilometre Array (SKA) is expected to directly detect the redshifted 21-cm signal from the neutral hydrogen present during the Cosmic Dawn. Temperature fluctuations from X-ray heating of the neutral…

Cosmology and Nongalactic Astrophysics · Physics 2019-05-15 Hannah E. Ross , Keri L. Dixon , Raghunath Ghara , Ilian T. Iliev , Garrelt Mellema

The formation redshift and abundance of the first stars and galaxies is highly sensitive to the build up of low mass dark matter halos as well as astrophysical feedback effects which modulate star formation in these low mass halos. The…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-30 Jo Verwohlt , Charlotte A. Mason , Julian B. Muñoz , Francis-Yan Cyr-Racine , Mark Vogelsberger , Jesús Zavala

The 21cm neutral hydrogen line is likely to be a key probe for studying the epoch of reionization and comic dawn in the forthcoming decades. This prospect stimulates the development of the theoretical basis for simulating the power spectrum…

Cosmology and Nongalactic Astrophysics · Physics 2017-09-14 Alexander A. Kaurov

The distribution of matter fluctuations in our universe is key for understanding the nature of dark matter and the physics of the early cosmos. Different observables have been able to map this distribution at large scales, corresponding to…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-01 Julian B. Muñoz , Cora Dvorkin , Francis-Yan Cyr-Racine

The cosmic 21-cm line of hydrogen is expected to be measured in detail by the next generation of radio telescopes. The enormous dataset from future 21-cm surveys will revolutionize our understanding of early cosmic times. We present a…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-11 Sudipta Sikder , Rennan Barkana , Itamar Reis , Anastasia Fialkov

Recently is has been suggested that the dearth of small halos around the Milky Way arises due to a modification of the primordial power spectrum of fluctuations from inflation. Such modifications would be expected to alter the formation of…

Astrophysics · Physics 2009-08-18 Martin White , Rupert A. C. Croft