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The ionosphere introduces chromatic distortions on low frequency radio waves, and thus poses a hurdle for 21-cm cosmology. In this paper we introduce time-varying chromatic ionospheric effects on simulated antenna temperature data of a…

Instrumentation and Methods for Astrophysics · Physics 2022-07-20 Emma Shen , Dominic Anstey , Eloy de Lera Acedo , Anastasia Fialkov

The redshifted 21 cm brightness distribution from neutral hydrogen is a promising probe into the cosmic dark ages, cosmic dawn, and re-ionization. LOFAR's Low Band Antennas (LBA) may be used in the frequency range 45 MHz to 85 MHz (30>z>16)…

Instrumentation and Methods for Astrophysics · Physics 2015-06-16 H. K. Vedantham , L. V. E. Koopmans , A. G. de Bruyn , S. J. Wijnholds , B. Ciardi , M. A. Brentjens

The deep learning technique has been employed in removing foreground contaminants from 21 cm intensity mapping, but its effectiveness is limited by the large dynamic range of the foreground amplitude. In this study, we develop a novel…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-13 Feng Shi , Haoxiang Chang , Le Zhang , Huanyuan Shan , Jiajun Zhang , Suiping Zhou , Ming Jiang , Zitong Wang

[Abridged] The spatially averaged global spectrum of the redshifted 21cm line has generated much experimental interest, for it is potentially a direct probe of the Epoch of Reionization and the Dark Ages. Since the cosmological signal here…

Cosmology and Nongalactic Astrophysics · Physics 2013-06-07 Adrian Liu , Jonathan R. Pritchard , Max Tegmark , Abraham Loeb

The ability to subtract foreground contamination from low-frequency observations is crucial to reveal the underlying 21 cm signal. The traditional line-of-sight methods can deal with the removal of diffuse emission and unresolved point…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Xiao-Chun Mao

The redshifted 21 cm absorption trough from cosmic atomic hydrogen is one of the most promising probes of the early Universe, but its detection is challenged by bright foregrounds and instrumental systematics. In this work we quantify the…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-27 Joe H. N. Pattison , John M. Cumner , Dominic J. Anstey , Saurabh Pegwal , Wessel Croukamp , Dirk I. L. de Villiers , Eloy de Lera Acedo

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

A measurement of the 21-cm global signal would be a revealing probe of the Dark Ages, the era of first star formation, and the Epoch of Reionization. It has remained elusive owing to bright galactic and extra-galactic foreground…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-20 Yordan D. Ignatov , Jonathan R. Pritchard , Yuqing Wu

The redshifted 21 cm line of cosmic atomic hydrogen is one of the most auspicious tools in deciphering the early Universe. Recovering this signal remains an ongoing problem for cosmologists in the field, with the signal being hidden behind…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-18 Joe H. N. Pattison , Jean Cavillot , Harry T. J. Bevins , Dominic J. Anstey , Eloy de Lera Acedo

We present a differentiable, end-to-end Bayesian forward modeling framework for line intensity mapping cosmology experiments, with a specific focus on low-frequency radio telescopes targeting the redshifted 21 cm line from neutral hydrogen…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-15 Nicholas Kern

Power spectrum estimators are an important tool in efforts to detect the 21 cm brightness temperature fluctuations from neutral hydrogen at early times. An initial detection will likely be statistical in nature, meaning that it will not be…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-24 Jacob Burba , Philip Bull , Michael J. Wilensky , Fraser Kennedy , Hugh Garsden , Katrine A. Glasscock

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 global 21 cm signal from the hyperfine transition of cosmic atomic hydrogen is theorised to track the state of the early Universe via the analysis of its absorption and emission with respect to the radio background. Detecting this…

Instrumentation and Methods for Astrophysics · Physics 2026-02-25 Joe H. N. Pattison , Dominic J. Anstey , Eloy de Lera Acedo

The highly redshifted 21 cm line of neutral hydrogen has become recognized as a unique probe of cosmology from relatively low redshifts (z ~ 1) up through the Epoch of Reionization (z ~ 8) and even beyond. To date, most work has focused on…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-23 Jonathan C. Pober

We present a comprehensive simulation-based study of the BayesEoR code for 21 cm power spectrum recovery when analytically marginalizing over foreground parameters. To account for covariance between the 21 cm signal and contaminating…

Instrumentation and Methods for Astrophysics · Physics 2023-02-09 Jacob Burba , Peter H. Sims , Jonathan C. Pober

We consider the evolution of the sky-averaged 21 cm background during the early phases of structure formation. Using simple analytic models, we calculate the thermal and ionization histories, assuming that stellar photons dominate the…

Astrophysics · Physics 2009-11-11 Steven Furlanetto

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

Current and upcoming 21-cm experiments will soon be able to map 21-cm spatial fluctuations in three dimensions for a wide range of redshifts. However, bright foreground contamination and the nature of radio interferometry create significant…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-01 Shu-Fan Chen , Kai-Feng Chen , Cora Dvorkin

The birth of the first luminous sources and the ensuing epoch of reionization are best studied via the redshifted 21-cm emission line, the signature of the first two imprinting the last. In this work we present a fully-Bayesian method,…

Cosmology and Nongalactic Astrophysics · Physics 2016-07-27 G. Bernardi , J. T. L. Zwart , D. Price , L. J. Greenhill , A. Mesinger , J. Dowell , T. Eftekhari , S. W. Ellingson , J. Kocz , F. Schinzel