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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

The 21 cm line provides a powerful probe of astrophysics and cosmology at high redshifts, but unlocking the potential of this probe requires the robust mitigation of foreground contaminants that are typically several orders of magnitude…

Cosmology and Nongalactic Astrophysics · Physics 2014-07-25 Adrian Liu , Aaron R. Parsons , Cathryn M. Trott

We apply two methods to estimate the 21~cm bispectrum from data taken within the Epoch of Reionisation (EoR) project of the Murchison Widefield Array (MWA). Using data acquired with the Phase II compact array allows a direct bispectrum…

A proposed method for dealing with foreground emission in upcoming 21-cm observations from the epoch of reionization is to limit observations to an uncontaminated window in Fourier space. Foreground emission can be avoided in this way,…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-23 Hannes Jensen , Suman Majumdar , Garrelt Mellema , Adam Lidz , Ilian T. Iliev , Keri L. Dixon

The radio interferometric closure phases can be a valuable tool for studying cosmological {H\scriptsize{I}}~from the early Universe. Closure phases have the advantage of being immune to element-based gains and associated calibration errors.…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-05 Himanshu Tiwari , Nithyanandan Thyagarajan , Cathryn M. Trott , Benjamin McKinley

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

Structure imprinted in foreground extragalactic point sources by ionospheric refraction has the potential to contaminate Epoch of Reionisation (EoR) power spectra of the 21~cm emission line of neutral hydrogen. The alteration of the spatial…

Deep imaging of structures from the Cosmic Dawn (CD) and the Epoch of Reionization (EoR) in five targeted fields is one of the highest priority scientific objectives for the Square Kilometre Array (SKA). Selecting 'quiet' fields, which…

Instrumentation and Methods for Astrophysics · Physics 2025-07-14 Xueying Zhang , Qian Zheng , Linhui Wu , Quan Guo , Stefan W. Duchesne , Mengfan He , Huanyuan Shan , Xiang-ping Wu , Melanie Johnston-Hollitt , Feiyu Zhao , Qingyuan Ma

The radio-wavelength detection of extensive air showers (EAS) initiated by cosmic-ray interactions in the Earth's atmosphere is a promising technique for investigating the origin of these particles and the physics of their interactions. The…

Instrumentation and Methods for Astrophysics · Physics 2021-03-29 A. Williamson , C. W. James , S. J. Tingay , S. J. McSweeney , S. M. Ord

Predictions for the ability of 21-cm interferometric experiments to discriminate Epoch of Reionization (EoR) signal models are typically limited by the simplicity of data models, whereby foreground signals and characteristics of the…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-29 Ainulnabilah Nasirudin , Steven Murray , Cathryn Trott , Bradley Greig , Ronniy Joseph , Chris Power

Observations of the 21cm Epoch of Reionization (EoR) signal are dominated by Galactic and extragalactic foregrounds. The need for foreground removal has led to the development of two main techniques, often referred to as "foreground…

We present techniques developed to calibrate and correct Murchison Widefield Array (MWA) low frequency (72-300 MHz) radio observations for polarimetry. The extremely wide field-of-view, excellent instantaneous (u, v)-coverage and…