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The post-reionization $(z \le 6)$ neutral hydrogen (HI) 21-cm intensity mapping signal holds the potential to probe the large scale structures, study the expansion history and constrain various cosmological parameters. Here we apply the…

The 21 cm hyperfine transition of neutral hydrogen offers a promising probe of the large scale structure of the universe before and during the Epoch of Reionization, when the first ionizing sources formed. Bright radio emission from…

Instrumentation and Methods for Astrophysics · Physics 2020-04-22 Adam E. Lanman , Jonathan C. Pober , Nicholas S. Kern , Eloy de Lera Acedo , David R. DeBoer , Nicolas Fagnoni

Cross-correlation between the redshifted 21 cm signal and Lyman-{\alpha} emitters (LAEs) is powerful tool to probe the Epoch of Reionization (EoR). Although the cross-power spectrum (PS) has an advantage of not correlating with foregrounds…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-25 S. Yoshiura , J. L. B. Line , K. Kubota , K. Hasegawa , K. Takahashi

The redshifted cosmological 21 cm signal emitted by neutral hydrogen during the first billion years of the universe is much fainter relative to other galactic and extragalactic radio emissions, posing a great challenge towards detection of…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-26 J. Kariuki Chege , C. H. Jordan , C. Lynch , C. M. Trott , J. L. B. Line , B. Pindor , S. Yoshiura

Measurements of the one-point probability distribution function and higher-order moments (variance, skewness, and kurtosis) of the high-redshift 21 cm fluctuations are among the most direct statistical probes of the non-Gaussian nature of…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-12 Piyanat Kittiwisit , Judd D. Bowman , Steven G. Murray , Bharat K. Gehlot , Daniel C. Jacobs , Adam P. Beardsley

Measurement of the power spectrum of high redshift 21 cm emission from neutral hydrogen probes the formation of the first luminous objects and the ionization of intergalactic medium by the first stars. However, the 21 cm signal at these…

Instrumentation and Methods for Astrophysics · Physics 2025-08-13 Katherine Elder , Daniel C. Jacobs , Maria Kovaleva

Large Scale Structures (LSS) in the universe can be traced using the neutral atomic hydrogen HI through its 21cm emission. Such a 3D matter distribution map can be used to test the Cosmological model and to constrain the Dark Energy…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 R. Ansari , J. E. Campagne , P. Colom , J. M. Le Goff , C. Magneville , J. M. Martin , M. Moniez , J. Rich , C. Yèche

Fluctuations in the redshifted 21 centimeter emission from neutral hydrogen probe the epoch of reionization. We examine the observability of this signal and the impact of extragalactic foreground radio sources. We use cosmological…

Astrophysics · Physics 2009-11-10 Tiziana Di Matteo , Benedetta Ciardi , Francesco Miniati

Detection of the \hi~ 21-cm power spectrum is one of the key science drivers of several ongoing and upcoming low-frequency radio interferometers. However, the major challenge in such observations come from bright foregrounds, whose accurate…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-29 Madhurima Choudhury , Abhirup Datta , Suman Majumdar

The 21-cm intensity mapping (IM) of neutral hydrogen (HI) is a promising tool to probe the large-scale structures. Sky maps of 21-cm intensities can be highly contaminated by different foregrounds, such as Galactic synchrotron radiation,…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-01 Elimboto Yohana , Yin-Zhe Ma , Di Li , Xuelei Chen , Wei-Ming Dai

Isocurvature perturbations expected from multi-field inflation models can leave unique signatures in the early Universe, but remain weakly constrained, especially on small scales. In this work, we investigate the constraining power of…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-19 Zhenfei Qin , Hayato Shimabukuro

The EoR 21-cm signal is expected to become highly non-Gaussian as reionization progresses. This severely affects the error-covariance of the EoR 21-cm power spectrum which is important for predicting the prospects of a detection with…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-14 Rajesh Mondal , Somnath Bharadwaj , Suman Majumdar

The recovery of an exoplanet's atmospheric parameters from its spectrum requires accurate knowledge of the spectral errors and covariances. Unfortunately, the complex image processing used in high-contrast integral-field spectrograph (IFS)…

Earth and Planetary Astrophysics · Physics 2016-12-14 Johnny P. Greco , Timothy D. Brandt

A number of experiments are currently working towards a measurement of the 21 cm signal from the Epoch of Reionization. Whether or not these experiments deliver a detection of cosmological emission, their limited sensitivity will prevent…

Upcoming 21-cm intensity surveys will use the hyperfine transition in emission to map out neutral hydrogen in large volumes of the universe. Unfortunately, large spatial scales are completely contaminated with spectrally smooth…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-27 Chirag Modi , Martin White , Anze Slosar , Emanuele Castorina

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

We seek to remove foreground contaminants from 21cm intensity mapping observations. We demonstrate that a deep convolutional neural network (CNN) with a UNet architecture and three-dimensional convolutions, trained on simulated…

Foregrounds with polarization states that are not smooth functions of frequency present a challenge to HI Epoch of Reionization (EoR) power spectrum measurements if they are not cleanly separated from the desired Stokes I signal. The…

Instrumentation and Methods for Astrophysics · Physics 2018-12-26 Zachary E. Martinot , James E. Aguirre , Saul A. Kohn , Immanuel Q. Washington

Mapping the distribution of neutral atomic hydrogen (HI) in the Universe through its 21 cm emission line provides a powerful cosmological probe to map the large-scale structures and shed light on various cosmological phenomena. The Baryon…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-20 Albin Joseph , Rajib Saha

21-cm intensity mapping (IM) is a powerful technique to probe the large-scale distribution of neutral hydrogen (HI) and extract cosmological information such as the baryon acoustic oscillation feature. A key challenge lies in recovering the…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-24 Zitong Wang , Feng Shi , Le Zhang , Yanming Liu , Xiaoping Li , Shulei Ni , Ming Jiang , Xiaofan Ma
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