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SKA is a new technology radio-telescope array, about two orders of magnitude more sensitive and rapid in sky surveys than present instruments. It will probe the dark age of the universe, just afer recombination, and during the epoch of…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-30 Francoise Combes

We present a study of internal reflection and cross coupling systematics in Phase I of the Hydrogen Epoch of Reionization Array (HERA). In a companion paper, we outlined the mathematical formalism for such systematics and presented…

We analyse the accuracy of radio interferometric gridding of visibilities with the aim to quantify the Epoch of Reionization (EoR) 21-cm power spectrum bias caused by gridding, ultimately to determine the suitability of different imaging…

Instrumentation and Methods for Astrophysics · Physics 2019-10-16 A. R. Offringa , F. Mertens , S. van der Tol , B. Veenboer , B. K. Gehlot , L. V. E. Koopmans , M. Mevius

We investigate the feasibility of measuring weak gravitational lensing using 21cm intensity mapping with special emphasis on the performance of the planned Square Kilometre Array (SKA). We find that the current design for SKA-Mid should be…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-04 A. Pourtsidou , R. Benton Metcalf

Hydrogen is the most abundant element in our Universe. The first generation of stars and galaxies produced photons that ionized hydrogen gas, driving a cosmological event known as the Epoch of Reionization (EoR). The upcoming Square…

Next-generation 21cm observations will enable imaging of reionization on very large scales. These images will contain more astrophysical and cosmological information than the power spectrum, and hence providing an alternative way to…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-27 Sultan Hassan , Adrian Liu , Saul Kohn , James E. Aguirre , Paul La Plante , Adam Lidz

We extend 21CMMC, a Monte Carlo Markov Chain sampler of 3D reionisation simulations, to perform parameter estimation directly on 3D light-cones of the cosmic 21cm signal. This brings theoretical analysis closer to the tomographic 21-cm…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-11 Bradley Greig , Andrei Mesinger

Recent simulations show the Epoch of Reionization (EoR) 21-cm signal to be inherently non-Gaussian whereby the error covariance matrix $\mathbf{C}_{ij}$ of the 21-cm power spectrum (PS) contains a trispectrum contribution that would be…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-01 Abinash Kumar Shaw , Somnath Bharadwaj , Rajesh Mondal

We test the hypothesis that limitations in the sky model used to calibrate an interferometric radio telescope, where the model contains extended radio sources, will generate bias in the Epoch of Reionisation (EoR) power spectrum. The…

Instrumentation and Methods for Astrophysics · Physics 2017-11-29 Cathryn M. Trott , Randall B. Wayth

A number of experiments are set to measure the 21-cm signal of neutral hydrogen from the Epoch of Reionization (EoR). The common denominator of these experiments are the large data sets produced, contaminated by various instrumental…

Precise subtraction of foreground sources is crucial for detecting and estimating 21cm HI signals from the Epoch of Reionization (EoR). We quantify how imperfect point source subtraction due to limitations of the measurement dataset yields…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Cathryn M. Trott , Randall B. Wayth , Steven J. Tingay

The ambitious scientific goals of SKA require a matching capability for calibration of instrumental and atmospheric propagation contributions as functions of time, frequency and position. The development of novel calibration algorithms to…

Instrumentation and Methods for Astrophysics · Physics 2022-02-01 María J. Rioja , Richard Dodson

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…

The 21 cm emission of neutral hydrogen is the most promising probe of the epoch of reionization(EoR). In the next few years, the SKA pathfinders will provide statistical measurements of this signal. Numerical simulations predicting these…

Astrophysics · Physics 2009-11-13 S. Baek , P. Di Matteo , B. Semelin , F. Combes , Y. Revaz

Radio astronomy is currently thriving with new large ground-based radio telescopes coming online in preparation for the upcoming Square Kilometre Array (SKA). Facilities like LOFAR, MeerKAT/SKA, ASKAP/SKA, and the future SKA-LOW bring…

Instrumentation and Methods for Astrophysics · Physics 2023-08-02 Benjamin Naoto Chiche , Julien N. Girard , Joana Frontera-Pons , Arnaud Woiselle , Jean-Luc Starck

Direct detection of the Epoch of Reionization (EoR) via the red-shifted 21-cm line will have unprecedented implications on the study of structure formation in the infant Universe. To fulfill this promise, current and future 21-cm…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-27 Abhik Ghosh , Florent Mertens , Leon V. E. Koopmans

New telescopes like the Square Kilometre Array (SKA) will push into a new sensitivity regime and expose systematics, such as direction-dependent effects, that could previously be ignored. Current methods for handling such systematics rely…

Instrumentation and Methods for Astrophysics · Physics 2015-05-22 Michelle Lochner , Iniyan Natarajan , Jonathan T. L. Zwart , Oleg Smirnov , Bruce A. Bassett , Nadeem Oozeer , Martin Kunz

Motivated by cutting-edge applications like cryo-electron microscopy (cryo-EM), the Multi-Reference Alignment (MRA) model entails the learning of an unknown signal from repeated measurements of its images under the latent action of a group…

Statistics Theory · Mathematics 2022-03-11 Subhro Ghosh , Philippe Rigollet

(Abridged) Noise considerations for experiments that aim to statistically estimate the 21 cm signal from high redshift neutral hydrogen during the Epoch of Reionisation (EoR) using interferometric data are typically computed assuming a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Cathryn M. Trott

Recent studies show that a reproducing kernel Hilbert space (RKHS) is not a suitable space to model functions by neural networks as the curse of dimensionality (CoD) cannot be evaded when trying to approximate even a single ReLU neuron…

Machine Learning · Statistics 2024-06-27 Fanghui Liu , Leello Dadi , Volkan Cevher