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During reionization, neutral hydrogen in the intergalactic medium (IGM) imprints a damping wing absorption feature on the spectrum of high-redshift quasars. A detection of this signature provides compelling evidence for a significantly…

The GMRT Epoch of Reionization (EoR) experiment is an ongoing effort to measure the power spectrum from neutral hydrogen at high redshift. We have previously reported an upper limit of (70 mK)^2 at wavenumbers of k=0.65 h/Mpc using a basic…

The neutral hydrogen (HI) power spectrum, measured from intensity fluctuations in the 21-cm background, offers insights into the large-scale structures (LSS) of our Universe in the post-reionization era (redshift $z<6$). A significant…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-10 Mohd Kamran , Martin Sahlén , Debanjan Sarkar , Suman Majumdar

The first measurements of the 21 cm brightness temperature power spectrum from the epoch of reionization will very likely be achieved in the near future by radio interferometric array experiments such as the Hydrogen Epoch of Reionization…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-22 Xiaosheng Zhao , Yi Mao , Benjamin D. Wandelt

Future 21 cm intensity mapping surveys such as SKA can provide precise information on the spatial distribution of the neutral hydrogen (HI) in the post-reionization epoch. This information will allow to test the standard LCDM paradigm and…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-26 Matteo Leo , Christian Arnold , Baojiu Li

The Largest Cluster Statistics\,(LCS) analysis of the redshifted 21\,cm maps has been demonstrated to be an efficient and robust method for following the time evolution of the largest ionized regions\,(LIRs) during the Epoch of…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-28 Samit Kumar Pal , Saswata Dasgupta , Abhirup Datta , Suman Majumdar , Satadru Bag , Prakash Sarkar

The observed power spectrum of redshifted 21cm fluctuations is known to be sensitive to the astrophysical properties of the galaxies that drove reionization. Thus, detailed measurements of the 21cm power spectrum and its evolution could…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Han-Seek Kim , J. Stuart B. Wyithe , Jaehong Park , C. G. Lacey

The Epoch of Reionization (EoR) 21-cm signal is expected to become increasingly non-Gaussian as reionization proceeds. We have used semi-numerical simulations to study how this affects the error predictions for the EoR 21-cm power spectrum.…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-03 Rajesh Mondal , Somnath Bharadwaj , Suman Majumdar , Apurba Bera , Ayan Acharyya

The epoch of reionization power spectrum is expected to evolve strongly with redshift, and it is this variation with cosmic history that will allow us to begin to place constraints on the physics of reionization. The primary obstacle to the…

The upcoming Square Kilometre Array Low Frequency (SKA-Low) interferometer will have the required sensitivity to detect the 21 cm line from neutral hydrogen during the Epoch of Reionisation (EoR). In preparation, we investigated the…

Instrumentation and Methods for Astrophysics · Physics 2025-09-25 E. Jong , C. Trott , C. D. Nunhokee , Q. Zheng

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,…

We model the 21-cm signal and LAE population evolution during the epoch of reionization in order to predict the 21cm-LAE cross-power spectrum. We employ high-dynamic-range simulations of the IGM to create models that are consistent with…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-01 Lewis H. Weinberger , Girish Kulkarni , Martin G. Haehnelt

Mapping of the neutral hydrogen (HI) 21-cm intensity fluctuations across redshifts promises a novel and powerful probe of cosmology. The neutral hydrogen gas mass density, $\Omega_{\rm HI}$ and bias parameter, $b_{\rm HI}$ are key…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-10 Hamsa Padmanabhan , T. Roy Choudhury , Alexandre Refregier

The measurements of the 21-cm brightness temperature fluctuations from the neutral hydrogen at the Epoch of Reionization (EoR) should inaugurate the next generation of cosmological observables. In this respect, many works have concentrated…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-10 Sebastien Clesse , Laura Lopez-Honorez , Christophe Ringeval , Hiroyuki Tashiro , Michel H. G. Tytgat

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…

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

Understanding properties of the first sources in the Universe using the redshifted \HI ~21-cm signal is one of the major aims of present and upcoming low-frequency experiments. We investigate the possibility of imaging the redshifted 21-cm…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-15 Raghunath Ghara , T. Roy Choudhury , Kanan K. Datta , Samir Choudhuri

An anisotropic power spectrum will have a clear signature in the 21cm radiation from high-redshift hydrogen. We calculate the expected power spectrum of the intensity fluctuations in neutral hydrogen from before the epoch of reionization,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Oscar F. Hernandez , Gilbert P. Holder

The redshifted 21cm line of neutral hydrogen (Hi), potentially observable at low radio frequencies (~50-200 MHz), is a promising probe of the physical conditions of the inter-galactic medium during Cosmic Dawn and the Epoch of Reionisation…

We discuss absolute calibration strategies for Phase I of the Hydrogen Epoch of Reionization Array (HERA), which aims to measure the cosmological 21 cm signal from the Epoch of Reionization (EoR). HERA is a drift-scan array with a 10 degree…