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The global 21 cm signal from Cosmic Dawn (CD) and the Epoch of Reionization (EoR), at redshifts $z \sim 6-30$, probes the nature of first sources of radiation as well as physics of the Inter-Galactic Medium (IGM). Given that the signal is…

Instrumentation and Methods for Astrophysics · Physics 2018-04-25 Saurabh Singh , Ravi Subrahmanyan , N. Udaya Shankar , Mayuri Sathyanarayana Rao , B. S. Girish , A. Raghunathan , R. Somashekar , K. S. Srivani

In the currently accepted model for cosmic baryon evolution, Cosmic Dawn and the Epoch of Reionization are significant times when first light from the first luminous objects emerged, transformed and subsequently ionized the primordial gas.…

Spectral distortions in the cosmic microwave background over the 40--200~MHz band are imprinted by neutral hydrogen in the intergalactic medium prior to the end of reionization. This signal, produced in the redshift range $z = 6-34$ at the…

SARAS is a correlation spectrometer purpose designed for precision measurements of the cosmic radio background and faint features in the sky spectrum at long wavelengths that arise from redshifted 21-cm from gas in the reionization epoch.…

Instrumentation and Methods for Astrophysics · Physics 2014-12-25 Nipanjana Patra , Ravi Subrahmanyan , A. Raghunathan , N. Udaya Shankar

Cosmic dawn represents critical juncture in cosmic history when the first population of stars emerged. The astrophysical processes that govern this transformation need to be better understood. The detection of redshifted 21-cm radiation…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-15 Yash Agrawal , K. Kavitha , Saurabh Singh

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…

Numerous experiments have been designed to investigate the Cosmic Dawn (CD) and Epoch of Reionization (EoR) by examining redshifted 21-cm emissions from neutral hydrogen. Detecting the global spectrum of redshifted 21-cm signals is…

Instrumentation and Methods for Astrophysics · Physics 2025-04-08 Feiyu Zhao , Quan Guo , Qian Zheng , Ruxi Liang , Pengfei Zhang , Yajun Wu , Junhua Gu , Zhao Yang , Yun Yu , Yan Huang , Tianyang Liu

Observations of the redshifted 21-cm line of atomic hydrogen have resulted in several upper limits on the 21-cm power spectrum and a tentative detection of the sky-averaged signal at $z\sim17$. Made with the EDGES Low-Band antenna, this…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-02 H. T. J. Bevins , A. Fialkov , E. de Lera Acedo , W. J. Handley , S. Singh , R. Subrahmanyan , R. Barkana

Interferometry of the cosmic 21-cm signal is set to revolutionise our understanding of the Epoch of Reionisation (EoR) and the Cosmic Dawn (CD). The culmination of ongoing efforts will be the upcoming Square Kilometre Array (SKA), which…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-08 Bradley Greig , Andrei Mesinger , Léon V. E. Koopmans

The astrophysics of cosmic dawn, when star formation commenced in the first collapsed objects, is predicted to be revealed as spectral and spatial signatures in the cosmic radio background at long wavelengths. The sky-averaged redshifted…

The study of the cosmic Dark Ages, Cosmic Dawn, and Epoch of Reionization (EoR) using the all-sky averaged redshifted HI 21cm signal, are some of the key science goals of most of the ongoing or upcoming experiments, for example, EDGES,…

Cosmology and Nongalactic Astrophysics · Physics 2019-12-24 Madhurima Choudhury , Abhirup Datta , Arnab Chakraborty

We introduce the Evolution of 21-cm Structure (EOS) project: providing periodic, public releases of the latest cosmological 21-cm simulations. 21-cm interferometry is set to revolutionize studies of the Cosmic Dawn (CD) and epoch of…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-27 Andrei Mesinger , Bradley Greig , Emanuele Sobacchi

The 21-cm signal from the Cosmic Dawn (CD) is likely to contain large fluctuations, with the most extreme astrophysical models on the verge of being ruled out by observations from radio interferometers. It is therefore vital that we…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-21 Hannah E. Ross , Sambit K. Giri , Keri L. Dixon , Raghunath Ghara , Ilian T. Iliev , Garrelt Mellema

The 21cm-galaxy cross-power spectrum is expected to be one of the promising probes of the Epoch of Reionization (EoR), as it could offer information about the progress of reionization and the typical scale of ionized regions at different…

The EDGES High-Band experiment aims to detect the sky-average brightness temperature of the $21$-cm signal from the Epoch of Reionization (EoR) in the redshift range $14.8 \gtrsim z \gtrsim 6.5$. To probe this redshifted signal, EDGES…

Instrumentation and Methods for Astrophysics · Physics 2017-01-25 Raul A. Monsalve , Alan E. E. Rogers , Judd D. Bowman , Thomas J. Mozdzen

The Epoch of Reionization (EoR) and Cosmic Dawn (CD) are pivotal stages during the first billion years of the universe, exerting a significant influence on the development of cosmic structure. The detection of the redshifted 21-cm signal…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-14 Anshuman Tripathi , Abhirup Datta , Aishrila Mazumder , Suman Majumdar

One of the aims of the Low Frequency Array (LOFAR) Epoch of Reionization (EoR) project is to measure the power spectrum of variations in the intensity of redshifted 21-cm radiation from the EoR. The sensitivity with which this power…

SARAS is a correlation spectrometer connected to a frequency independent antenna that is purpose-designed for precision measurements of the radio background at long wavelengths. The design, calibration and observing strategies admit…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-23 Nipanjana Patra , Ravi Subrahmanyan , Shiv Sethi , N. Udaya Shankar , A. Raghunathan

The Dark Ages, probed by the redshifted 21-cm signal, is the ideal epoch for a new rigorous test of the standard LCDM cosmological model. Divergences from that model would indicate new physics, such as dark matter decay (heating) or…

Detecting redshifted 21cm emission from neutral hydrogen in the early Universe promises to give direct constraints on the epoch of reionization (EoR). It will, though, be very challenging to extract the cosmological signal (CS) from…

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