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The light-cone (LC) effect causes the mean as well as the statistical properties of the redshifted 21-cm signal $T_{\rm b}(\hat{\bf n},\nu)$ to change with frequency $\nu$ (or cosmic time). Consequently, the statistical homogeneity…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-05 Rajesh Mondal , Abinash Kumar Shaw , Ilian T. Iliev , Somnath Bharadwaj , Kanan K. Datta , Suman Majumdar , Anjan K. Sarkar , Keri L. Dixon

The light-cone effect breaks the periodicity and statistical homogeneity (ergodicity) along the line-of-sight direction of cosmological emission/absorption line surveys. The spherically averaged power spectrum (SAPS), which by definition…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-31 Rajesh Mondal , Garrelt Mellema , Steven G. Murray , Bradley Greig

The rapid evolution of the cosmological neutral hydrogen (HI) distribution during the EoR is imprinted along the line of sight (LoS) in the redshifted 21-cm signal due to the light cone (LC) effect. The LC EoR 21-cm signal ceases to be…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-06 Suman Pramanick , Somnath Bharadwaj , Khandakar Md Asif Elahi , Rajesh Mondal

The reported detection of the global 21-cm signal by the EDGES collaboration is significantly stronger than standard astrophysical predictions. One possible explanation is an early radio excess above the cosmic microwave background. Such a…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-12 Sudipta Sikder , Rennan Barkana , Anastasia Fialkov , Itamar Reis

Using a suite of detailed numerical simulations we estimate the level of anisotropy generated by the time evolution along the light cone of the 21cm signal from the epoch of reionization. Our simulations include the physics necessary to…

Cosmology and Nongalactic Astrophysics · Physics 2014-01-09 Karolina Zawada , Benoit Semelin , Patrick Vonlanthen , Sunghye Baek , Yves Revaz

One of the most promising ways to study the epoch of reionization (EoR) is through radio observations of the redshifted 21-cm line emission from neutral hydrogen. These observations are complicated by the fact that the mapping of redshifts…

Observations of redshifted 21-cm radiation from neutral hydrogen during the epoch of reionization (EoR) are considered to constitute the most promising tool to probe that epoch. One of the major goals of the first generation of low…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Kanan K. Datta , Garrelt Mellema , Yi Mao , Ilian T. Iliev , Paul R. Shapiro , Kyungjin Ahn

The light-cone (LC) effect causes the Epoch of Reionization (EoR) 21-cm signal $T_{\rm b} (\hat{\bf{n}}, \nu)$ to evolve significantly along the line of sight (LoS) direction $\nu$. In the first part of this paper, we present a method to…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-12 Rajesh Mondal , Somnath Bharadwaj , Kanan K. Datta

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 line of sight direction in the redshifted 21-cm signal coming from the cosmic dawn and the epoch of reionization is quite unique in many ways compared to any other cosmological signal. Different unique effects, such as the evolution…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-28 Suman Majumdar , Kanan K. Datta , Raghunath Ghara , Rajesh Mondal , T. Roy Choudhury , Somnath Bharadwaj , Sk. Saiyad Ali , Abhirup Datta

Details of various unknown physical processes during the cosmic dawn and the epoch of reionization can be extracted from observations of the redshifted 21-cm signal. These observations, however, will be affected by the evolution of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-08-14 Raghunath Ghara , Kanan K. Datta , T. Roy Choudhury

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

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

The redshifted cosmic 21 cm line signal of neutral hydrogen provides the possibility to constrain the matter power spectrum. Cross correlating temperature maps at different frequencies (corresponding to different redshifts along the line of…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-20 Kerstin E. Kunze

We report on a measurement of the angular power spectrum of the anisotropy in the Cosmic Microwave Background. The anisotropy is measured in 23 different multipole bands from l=54 (~3 deg) to l=404 (~0.45 deg) and in 6 frequency bands from…

Astrophysics · Physics 2009-10-28 C. B. Netterfield , M. J. Devlin , N. Jarosik , L. Page , E. J. Wollack

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…

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

We extend 21CMMC, a Monte Carlo Markov Chain sampler of 3D reionisation simulations, to perform parameter estimation directly on 3D light-cones of the cosmic 21cm signal. This brings theoretical analysis closer to the tomographic 21-cm…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-11 Bradley Greig , Andrei Mesinger

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

The 21-cm absorption feature reported by the EDGES collaboration is several times stronger than that predicted by traditional astrophysical models. If genuine, a deeper absorption may lead to stronger fluctuations on the 21-cm signal on…

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