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Related papers: Large 21 cm signals from AGN-dominated reionizatio…

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The first generation of redshifted 21 cm detection experiments, carried out with arrays like LOFAR, MWA and GMRT, will have a very low signal-to-noise ratio per resolution element (\sim 0.2). In addition, whereas the variance of the…

The power spectra of the redshifted 21-cm signal from the Epoch of Reionization (EoR) contain information about the ionization and thermal states of the intergalactic medium (IGM), and depend on the properties of the EoR sources. Recently,…

Measurement of fluctuations in diffuse HI 21 cm background radiation from the post-reionization epoch (z < 6) is a promising avenue to probe the large-scale structure of the Universe and understand the evolution of galaxies. We observe the…

21cm emission from residual neutral hydrogen after the epoch of reionization can be used to trace the cosmological power spectrum of density fluctuations. Using a Fisher matrix formulation, we provide a detailed forecast of the constraints…

Astrophysics · Physics 2009-11-13 Eli Visbal , Abraham Loeb , Stuart Wyithe

We compute the bispectra of the 21cm signal during the Epoch of Reionization for three different reionization scenarios that are based on a dark matter N-body simulation combined with a self-consistent, semi-numerical model of galaxy…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-08 Anne Hutter , Catherine A. Watkinson , Jacob Seiler , Pratika Dayal , Manodeep Sinha , Darren J. Croton

During the transition from a neutral to a fully reionized universe, scattering of cosmic microwave background (CMB) photons via free-electrons leads to a new anisotropy contribution to the temperature distribution. If the reionization…

Astrophysics · Physics 2009-11-10 Asantha Cooray

We report constraints on the global $21$ cm signal due to neutral hydrogen at redshifts $14.8 \geq z \geq 6.5$. We derive our constraints from low foreground observations of the average sky brightness spectrum conducted with the EDGES…

Cosmology and Nongalactic Astrophysics · Physics 2017-10-04 Raul A. Monsalve , Alan E. E. Rogers , Judd D. Bowman , Thomas J. Mozdzen

21cm-galaxy cross-correlation will play a key role in confirming the cosmological 21cm signal. We investigate which survey configurations detect the 21cm-LAE cross-correlation signal, and assess its ability to distinguish reionisation…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-18 Anne Hutter , Caroline Heneka

We present simulations of the 21-cm signal during the epoch of reionization. We focus on properly modeling the absorption regime in the presence of inhomogeneous Wouthuysen-Field effect and X-ray heating. We ran radiative transfer…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 S. Baek , B. Semelin , P. Di Matteo , Y. Revaz , F. Combes

Upon an expansion of all of the searches for redshifted HI 21-cm absorption (0.0021 < z 5.19), we update recent results regarding the detection of 21-cm in the non-local Universe. Specifically, we confirm that photo-ionisation of the gas is…

Astrophysics of Galaxies · Physics 2018-03-14 S. J. Curran , S. W. Duchesne

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

Cosmic reionization represents the latest phase transition in the Universe, when the Lyman continuum (LyC) photons turned the intergalactic medium (IGM) from neutral to highly ionized. It has long been debated whether galaxies or active…

Astrophysics of Galaxies · Physics 2025-10-09 Danyang Jiang , Linhua Jiang , Shengxiu Sun , Weiyang Liu , Shuqi Fu

Measurement of the spatial distribution of neutral hydrogen via the redshifted 21 cm line promises to revolutionize our knowledge of the epoch of reionization and the first galaxies, and may provide a powerful new tool for observational…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Miguel F. Morales , J. Stuart B. Wyithe

Absorption or emission against the cosmic microwave background radiation (CMB) may be observed in the redshifted 21cm line if the spin temperature of the neutral intergalactic medium prior to reionization differs from the CMB temperature.…

Astrophysics · Physics 2009-12-10 Tiziana Di Matteo , Rosalba Perna , Tom Abel , Martin J. Rees

The morphology of the 21-cm signal emitted by the neutral hydrogen present in the intergalactic medium (IGM) during the Epoch of Reionization (EoR) depends both on the properties of the sources of ionizing radiation and on the underlying…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-04 Leon Noble , Mohd Kamran , Suman Majumdar , Chandra Shekhar Murmu , Raghunath Ghara , Garrelt Mellema , Ilian T. Iliev , Jonathan R. Pritchard

We explore how the characteristics of the cross-correlation functions between the 21cm emission from the spin-flip transition of neutral hydrogen (HI) and early Lyman-$\alpha$ (Ly$\alpha$) radiation emitting galaxies (Ly$\alpha$ emitters,…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-09 Anne Hutter , Caroline Heneka , Pratika Dayal , Stefan Gottlöber , Andrei Mesinger , Maxime Trebitsch , Gustavo Yepes

The redshifted 21-cm line of distant neutral H atoms provides a probe of the cosmic ``dark ages'' and the epoch of reionization (``EOR'') which ended them. The radio continuum produced by this redshifted line can be seen in absorption or…

Astrophysics · Physics 2009-11-13 Paul R. Shapiro , Ilian T. Iliev , Garrelt Mellema , Ue-Li Pen , Hugh Merz

In the past, high-z AGNs were given a minor role as possible drivers of reionization, despite initial evidences in favor of their large space densities at low luminosities by Chandra and HST. Recent observations from JWST are finding…

Our understanding of the intergalactic medium at redshifts $z=5$-$6$ has improved considerably in the last few years due to the discovery of quasars with $z>6$ that enable Lyman-$\alpha$ forest studies at these redshifts. A realisation from…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-08 Janakee Raste , Girish Kulkarni , Laura C. Keating , Martin G. Haehnelt , Jonathan Chardin , Dominique Aubert

Preliminary results are presented from a simple, single-antenna experiment designed to measure the all-sky radio spectrum between 100 and 200 MHz. The system used an internal comparison-switching scheme to reduce non-smooth instrumental…

Astrophysics · Physics 2009-11-13 Judd D. Bowman , Alan E. E. Rogers , Jacqueline N. Hewitt