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Related papers: The 21cm Power Spectrum After Reionization

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The redshifted 21-cm signal from the epoch of reionization (EoR) directly probes the ionization and thermal states of the intergalactic medium during that period. In particular, the distribution of the ionized regions around the radiating…

Modern cosmological surveys cover extremely large volumes and map fluctuations on scales reaching gigaparsecs. As a result, it is no longer a valid assumption to ignore cosmological evolution along the line of sight from one end of the…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-23 Mattéo Blamart , Adrian Liu

We investigate whether the redshift evolution of the fixed-$k$ dimensionless 21 cm power spectrum, $\Delta^2_{21}(k, z)$, contains sufficient information to reconstruct reionization histories $x_{\mathrm{HI}}(z)$ with artificial neural…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-21 Yu-Le Wang , Hayato Shimabukuro

The cosmic 21-cm signal promises to revolutionize studies of the Epoch of Reionization (EoR). Radio interferometers are aiming for a preliminary, low signal-to-noise (S/N) detection of the 21-cm power spectrum. Cross-correlating 21-cm with…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-09 Samuel Gagnon-Hartman , James E. Davies , Andrei Mesinger

We explore the ability of observations of the global brightness temperature of the 21-cm signal to constrain the reionization history and the properties of the ionizing sources. In order to describe the reionization signal, we employ either…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Andrea Morandi , Rennan Barkana

One of the most exciting probes of the early phases of structure formation and reionization is the spin-flip line of neutral hydrogen, with a rest wavelength of 21 cm. This chapter introduces the physics of this transition and the…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-27 Steven R. Furlanetto

Neutral hydrogen (HI) 21-cm Intensity Mapping (IM) holds the potential to map the large-scale structures in the Universe over a wide redshift range $(z \lesssim 5.5)$, measure cosmological parameters, and shed light on the nature of dark…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-27 Minal Chhabra , Somnath Bharadwaj

Long wavelength spectral distortions in the Cosmic Microwave Background arising from the 21-cm transition in neutral Hydrogen are a key probe of Cosmic Dawn and the Epoch of Reionization. These features may reveal the nature of the first…

In this paper we use radiative transfer + N-body simulations to explore the feasibility of measurements of cross-correlations between the 21cm field observed by the Square Kilometer Array (SKA) and high-z Lyman Alpha Emitters (LAEs)…

Cosmology and Nongalactic Astrophysics · Physics 2020-02-05 Dijana Vrbanec , Benedetta Ciardi , Vibor Jelic , Hannes Jensen , Ilian T. Iliev , Garrelt Mellema , Saleem Zaroubi

The 21cm line probes the evolution of matter perturbations over a wide range of redshifts, from the dark ages down to the completion of reionization. Observing the 21cm cosmological signal will extend our understanding of the evolution of…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-26 Xue-Wen Liu , Caroline Heneka , Luca Amendola

Understanding the nature of dark energy is one of the most outstanding problems in cosmology at present. In last twenty years, cosmological observations related to SNIa, Cosmic Microwave Background Radiation, Baryon Acoustic Oscillations…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-01 Bikash R. Dinda , Anjan A Sen , Tirthankar Roy Choudhury

The large-scale structure of the Universe can be mapped with unresolved intensity fluctuations of the 21 cm line. The power spectrum of the intensity fluctuations has been proposed as a probe of the baryon acoustic oscillations at low to…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Yan Gong , Xuelei Chen , Marta Silva , Asantha Cooray , Mario G. Santos

We present new upper limits on the 21-cm signal power spectrum from the Epoch of Reionization (EoR), at redshifts $z \approx 10.1, 9.1, \text{ and } 8.3$, based on reprocessed observations from the Low-Frequency Array (LOFAR). The analysis…

The redshifted 21-cm signal emitted by neutral Hydrogen (HI) is a promising probe to understand the evolution of the topology of ionized regions during the Epoch of Reionization (EoR). The topology of ionized regions allows us to infer the…

We study 21cm and Ly$\mathrm{\alpha}$ fluctuations, as well as H$\mathrm{\alpha}$, while distinguishing between Ly$\mathrm{\alpha}$ emission of galactic, diffuse, and scattered intergalactic medium (IGM) origin. Cross-correlation…

Cosmology and Nongalactic Astrophysics · Physics 2017-10-18 Caroline Heneka , Asantha Cooray , Chang Feng

We investigate how precisely we can determine the nature of dark energy such as the equation of state (EoS) and its time dependence by using future observations of 21 cm fluctuations at the epoch of reionization (6.8 <~ z <~ 10) such as…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-07 Kazunori Kohri , Yoshihiko Oyama , Toyokazu Sekiguchi , Tomo Takahashi

The X-ray background during the epoch of reionization is currently poorly constrained. We demonstrate that it is possible to use first generation 21 cm experiments to calibrate it. Using the semi-numerical simulation, 21cmFAST, we calculate…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Pierre Christian , Abraham Loeb

We study the prospects for extracting detailed statistical properties of the neutral Hydrogen distribution during the era of reionization using the brightness temperature fluctuations from redshifted 21 cm line emission. Detection of this…

Astrophysics · Physics 2009-11-10 M. G. Santos , A. Cooray , L. Knox

We study the observability of the reionization epoch through the 21 cm hyperfine transition of neutral hydrogen. We use a high-resolution cosmological simulation (including hydrodynamics) together with a fast radiative transfer algorithm to…

Astrophysics · Physics 2009-11-07 Steven Furlanetto , Aaron Sokasian , Lars Hernquist

During the Epoch of reionisation, the intergalactic medium is reionised by the UV radiation from the first generation of stars and galaxies. One tracer of the process is the 21 cm line of hydrogen that will be observed by the Square…

Cosmology and Nongalactic Astrophysics · Physics 2023-11-29 Julien Hiegel , Emilie Thélie , Dominique Aubert , Jonathan Chardin , Nicolas Gillet , Pierre Galois , Nicolas Mai , Pierre Ocvirk , Rodrigo Ibata