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The Epoch of Reionization (EoR), when the first luminous sources ionised the intergalactic medium, represents a new frontier in cosmology. The Square Kilometre Array Observatory (SKAO) will offer unprecedented insights into this era through…

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

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 report the most sensitive upper limits to date on the 21 cm epoch of reionization power spectrum using 94 nights of observing with Phase I of the Hydrogen Epoch of Reionization Array (HERA). Using similar analysis techniques as in…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-28 The HERA Collaboration , Zara Abdurashidova , Tyrone Adams , James E. Aguirre , Paul Alexander , Zaki S. Ali , Rushelle Baartman , Yanga Balfour , Rennan Barkana , Adam P. Beardsley , Gianni Bernardi , Tashalee S. Billings , Judd D. Bowman , Richard F. Bradley , Daniela Breitman , Philip Bull , Jacob Burba , Steve Carey , Chris L. Carilli , Carina Cheng , Samir Choudhuri , David R. DeBoer , Eloy de Lera Acedo , Matt Dexter , Joshua S. Dillon , John Ely , Aaron Ewall-Wice , Nicolas Fagnoni , Anastasia Fialkov , Randall Fritz , Steven R. Furlanetto , Kingsley Gale-Sides , Hugh Garsden , Brian Glendenning , Adélie Gorce , Deepthi Gorthi , Bradley Greig , Jasper Grobbelaar , Ziyaad Halday , Bryna J. Hazelton , Stefan Heimersheim , Jacqueline N. Hewitt , Jack Hickish , Daniel C. Jacobs , Austin Julius , Nicholas S. Kern , Joshua Kerrigan , Piyanat Kittiwisit , Saul A. Kohn , Matthew Kolopanis , Adam Lanman , Paul La Plante , David Lewis , Adrian Liu , Anita Loots , Yin-Zhe Ma , David H. E. MacMahon , Lourence Malan , Keith Malgas , Cresshim Malgas , Matthys Maree , Bradley Marero , Zachary E. Martinot , Lisa McBride , Andrei Mesinger , Jordan Mirocha , Mathakane Molewa , Miguel F. Morales , Tshegofalang Mosiane , Julian B. Muñoz , Steven G. Murray , Vighnesh Nagpal , Abraham R. Neben , Bojan Nikolic , Chuneeta D. Nunhokee , Hans Nuwegeld , Aaron R. Parsons , Robert Pascua , Nipanjana Patra , Samantha Pieterse , Yuxiang Qin , Nima Razavi-Ghods , James Robnett , Kathryn Rosie , Mario G. Santos , Peter Sims , Saurabh Singh , Craig Smith , Hilton Swarts , Jianrong Tan , Nithyanandan Thyagarajan , Michael J. Wilensky , Peter K. G. Williams , Pieter van Wyngaarden , Haoxuan Zheng

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…

Improvements in current instruments and the advent of next-generation instruments will soon push observational 21 cm cosmology into a new era, with high significance measurements of both the power spectrum and the mean ("global") signal of…

Cosmology and Nongalactic Astrophysics · Physics 2016-02-08 Adrian Liu , Aaron R. Parsons

Observations of the redshifted 21-cm signal emitted by neutral hydrogen represent a promising probe of large-scale structure in the universe. However, cosmological 21-cm signal is challenging to observe due to astrophysical foregrounds…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-07 Haochen Wang , Juan Mena-Parra , Tianyue Chen , Kiyoshi Masui

[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 overwhelming foreground contamination hinders the accurate detection of the 21-cm signal of neutral hydrogen during the Epoch of Reionization (EoR). Among various foreground components, the Galactic free-free emission is less studied,…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-11 Xiaoli Lian , Haiguang Xu , Zhenghao Zhu , Dan Hu

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

A detection of the predicted anticorrelation between 21cm and either Ly-alpha or H-alpha from the Epoch of Reionization (EOR) would be a powerful probe of the first galaxies. While 3D intensity maps isolate foregrounds in low k_\parallel…

Cosmology and Nongalactic Astrophysics · Physics 2017-11-06 Abraham R. Neben , Brian Stalder , Jacqueline N. Hewitt , John L. Tonry

Radio Frequency Interference (RFI) is one of the systematic challenges preventing 21cm interferometric instruments from detecting the Epoch of Reionization. To mitigate the effects of RFI on data analysis pipelines, numerous inpaint…

We present in this paper a new Bayesian semi-blind approach for foreground removal in observations of the 21-cm signal with interferometers. The technique, which we call HIEMICA (HI Expectation-Maximization Independent Component Analysis),…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-20 Le Zhang , Emory F. Bunn , Ata Karakci , Andrei Korotkov , P. M. Sutter , Peter T. Timbie , Gregory S. Tucker , Benjamin D. Wandelt

The redshifted 21 cm line of neutral hydrogen is a promising probe of the Epoch of Reionization (EoR). However, its detection requires a thorough understanding and control of the systematic errors. We study two systematic biases observed in…

The Epoch of Reionization (EoR) is an uncharted era in our Universe's history during which the birth of the first stars and galaxies led to the ionization of neutral hydrogen in the intergalactic medium. There are many experiments…

Experiments designed to measure the redshifted 21~cm line from the Epoch of Reionization (EoR) are challenged by strong astrophysical foreground contamination, ionospheric distortions, complex instrumental response and other different types…

Observation of the 21cm line signal from neutral hydrogen during the Epoch of Reionization is challenging due to extremely bright Galactic and extragalactic foregrounds and complicated instrumental calibration. A reasonable approach for…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-12 S. Yoshiura , K. Ichiki , B. Pindor , K. Takahashi , H. Tashiro , C. M. Trott

The high-redshift 21 cm signal from the Epoch of Reionization (EoR) is a promising observational probe of the early universe. Current- and next-generation radio interferometers such as the Hydrogen Epoch of Reionization Array (HERA) and…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-13 Paul La Plante , Adam Lidz , James Aguirre , Saul Kohn

Observing the neutral hydrogen distribution across the Universe via redshifted 21cm line intensity mapping constitutes a powerful probe for cosmology. However, the redshifted 21cm signal is obscured by the foreground emission from our…

Future high redshift 21-cm experiments will suffer from a high degree of contamination, due both to astrophysical foregrounds and to non-astrophysical and instrumental effects. In order to reliably extract the cosmological signal from the…

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