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As a result of our limited data on reionization, the total optical depth for electron scattering, $\tau$, limits precision measurements of cosmological parameters from the Cosmic Microwave Background (CMB). It was recently shown that the…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-27 Anastasia Fialkov , Abraham Loeb

Emulation of the Global (sky-averaged) 21-cm signal with neural networks has been shown to be an essential tool for physical signal modelling. In this paper we present globalemu, a Global 21-cm signal emulator that uses redshift as a…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-18 H. T. J. Bevins , W. J. Handley , A. Fialkov , E. de Lera Acedo , K. Javid

We introduce a Bayesian null-stream method to constrain calibration errors in closed-geometry gravitational-wave (GW) detector networks. Unlike prior methods requiring electromagnetic counterparts or waveform models, this method uses…

General Relativity and Quantum Cosmology · Physics 2025-10-09 Isaac C. F. Wong , Francesco Cireddu , Milan Wils , Tom Colemont , Harsh Narola , Chris Van Den Broeck , Tjonnie G. F. Li

High fidelity radio interferometric data calibration that minimises spurious spectral structure in the calibrated data is essential in astrophysical applications, such as 21 cm cosmology, which rely on knowledge of the relative spectral…

Instrumentation and Methods for Astrophysics · Physics 2022-10-26 Peter H. Sims , Jonathan C. Pober , Jonathan L. Sievers

Instruments targeting 21~cm emission at high redshifts need a spectral dynamic range of better than ten thousand to distinguish the 21~cm background against bright foregrounds. Systematics arising from the antenna pattern are a leading…

Instrumentation and Methods for Astrophysics · Physics 2026-05-21 Daniel C. Jacobs

Radio interferometers designed to probe the 21cm signal from Cosmic Dawn and the Epoch of Reionisation must contend with systematic effects that make it difficult to achieve sufficient dynamic range to separate the 21cm signal from…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-24 Fraser Kennedy , Philip Bull , Michael Wilensky , Jacob Burba , Samir Choudhuri

High precision measurements are essential to solve major scientific and technological challenges, from gravitational wave detection to healthcare diagnostics. Quantum sensing delivers greater precision, but an in-depth optimisation of…

Cosmological measurements of the 21-cm line of neutral hydrogen are poised to dramatically enhance our understanding of the early universe. In particular, both the epochs of reionization and cosmic dawn remain largely uncharted, and the…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-13 Julian B. Muñoz , Francis-Yan Cyr-Racine

This paper develops a Bayesian network-based method for the calibration of multi-physics models, integrating various sources of uncertainty with information from computational models and experimental data. We adopt the Kennedy and O'Hagan…

Data Analysis, Statistics and Probability · Physics 2012-06-25 You Ling , Joshua Mullins , Sankaran Mahadevan

We are approaching a new era to probe the 21-cm neutral hydrogen signal from the period of cosmic dawn. This signal offers a unique window to the virgin Universe, e.g., to study dark matter models with different small-scale behaviours. The…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-21 Venno Vipp , Andi Hektor , Gert Hütsi

The current and future cosmic microwave background (CMB) experiments fielding kilo-pixel arrays of transition-edge sensor (TES) bolometers require accurate and robust gain calibration methods. We simplify and refactor the standard TES model…

A recent observation by the EDGES collaboration shows a strong absorption signal in the global 21-cm spectrum from around a redshift of $z = 17$. This absorption is stronger than the maximum prediction by existing models and indicates that…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-11 Suman Chatterjee , Somnath Bharadwaj

[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

Precision calibration poses challenges to experiments probing the redshifted 21-cm signal of neutral hydrogen from the Cosmic Dawn and Epoch of Reionization (z~30-6). In both interferometric and global signal experiments, systematic…

As the size of quantum devices continues to grow, the development of scalable methods to characterise and diagnose noise is becoming an increasingly important problem. Recent methods have shown how to efficiently estimate Hamiltonians in…

Quantum Physics · Physics 2019-12-18 Tim J. Evans , Robin Harper , Steven T. Flammia

The EDGES High-Band experiment aims to detect the sky-average brightness temperature of the $21$-cm signal from the Epoch of Reionization (EoR) in the redshift range $14.8 \gtrsim z \gtrsim 6.5$. To probe this redshifted signal, EDGES…

Instrumentation and Methods for Astrophysics · Physics 2017-01-25 Raul A. Monsalve , Alan E. E. Rogers , Judd D. Bowman , Thomas J. Mozdzen

We describe a Bayesian framework for estimating the time-domain noise covariance of CMB observations, typically parametrized in terms of a 1/f frequency profile. This framework is based on the Gibbs sampling algorithm, which allows for…

Instrumentation and Methods for Astrophysics · Physics 2015-05-30 I. K. Wehus , S. K. Næss , H. K. Eriksen

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

In critical decision support systems based on medical imaging, the reliability of AI-assisted decision-making is as relevant as predictive accuracy. Although deep learning models have demonstrated significant accuracy, they frequently…

Computer Vision and Pattern Recognition · Computer Science 2026-02-13 Hua Xu , Julián D. Arias-Londoño , Juan I. Godino-Llorente

The Bayesian Land Surface Temperature estimator previously developed has been extended to include the effects of imperfectly known gain and offset calibration errors. It is possible to treat both gain and offset as nuisance parameters and,…

Data Analysis, Statistics and Probability · Physics 2009-11-11 J. A. Morgan