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Understanding the first billion years of the universe requires studying two critical epochs: the Epoch of Reionization (EoR) and Cosmic Dawn (CD). However, due to limited data, the properties of the Intergalactic Medium (IGM) during these…

Instrumentation and Methods for Astrophysics · Physics 2024-10-18 Anshuman Tripathi , Gursharanjit Kaur , Abhirup Datta , Suman Majumdar

Radiomics-based machine learning models show promise for clinical decision support but are vulnerable to distribution shifts caused by variations in imaging protocols, positioning, and segmentation. This study systematically investigates…

Machine Learning · Computer Science 2025-10-30 Sarmad Ahmad Khan , Simon Bernatz , Zahra Moslehi , Florian Buettner

The recently claimed anomaly in the measurement of the 21 cm hydrogen absorption signal by EDGES at $z\sim 17$, if cosmological, requires the existence of new physics. The possible attempts to resolve the anomaly rely on either (i) cooling…

Future observations of 21 cm emission from neutral hydrogen survey will become a promising approach to probe the large scale structure of Universe. In this paper, we investigate the impacts of Square Kilometer Array (SKA) 21 cm observation…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-12 Jing-Fei Zhang , Li-Yang Gao , Dong-Ze He , Xin Zhang

This paper develops goodness of fit statistics that can be used to formally assess Markov random field models for spatial data, when the model distributions are discrete or continuous and potentially parametric. Test statistics are formed…

Statistics Theory · Mathematics 2012-05-29 Mark S. Kaiser , Soumendra N. Lahiri , Daniel J. Nordman

We study the behavior of internal signal chain reflections and antenna cross coupling as systematics for 21 cm cosmological surveys. We outline the mathematics for how these systematics appear in interferometric visibilities and describe…

Instrumentation and Methods for Astrophysics · Physics 2019-10-28 Nicholas S. Kern , Aaron R. Parsons , Joshua S. Dillon , Adam E. Lanman , Nicolas Fagnoni , Eloy de Lera Acedo

The 21 cm signal from neutral hydrogen atom is almost the only way to directly probe the Dark Ages. The Dark Ages 21 cm signal, observed at frequencies below 50 MHz, can serve as a powerful probe of cosmology, as the standard cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-03 Shintaro Yoshiura , Fumiya Okamatsu , Tomo Takahashi

One approach to extracting the global 21-cm signal from total-power measurements at low radio frequencies is to parametrize the different contributions to the data and then fit for these parameters. We examine parametrizations of the 21-cm…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-04 Geraint J. A. Harker , Jordan Mirocha , Jack O. Burns , Jonathan R. Pritchard

Purpose: Deformable image registration (DIR) is critical in adaptive radiation therapy (ART) to account for anatomical changes. Conventional intensity-based DIR methods often fail when image intensities differ. This study evaluates a hybrid…

Medical Physics · Physics 2024-11-27 Keyur D. Shah , James A. Shackleford , Nagarajan Kandasamy , Gregory C. Sharp

The China Space Station Telescope (CSST) is a forthcoming space-based optical telescope designed to co-orbit with the Chinese Space Station. With a planned slitless spectroscopic survey spanning a broad wavelength range of $255-1000$nm and…

The key probes of the growth of large-scale structure are its rate $f$ and amplitude $\sigma_8$. Redshift space distortions in the galaxy power spectrum allow us to measure only the combination $f\sigma_8$, which can be used to constrain…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-14 Louis Perenon , Stéphane Ilić , Roy Maartens , Alvaro de la Cruz-Dombriz

Accurate detection of the cosmological 21-cm global signal requires galactic foreground models which can remove power over ~$10^6$. Although foreground and global signal models unavoidably exhibit overlap in their vector-spaces inducing…

Cosmology and Nongalactic Astrophysics · Physics 2023-10-31 Joshua J. Hibbard , David Rapetti , Jack O. Burns , Nivedita Mahesh , Neil Bassett

We propose a new and rather stringent criterion for testing the goodness of fit between a theory and experiment. It is motivated by the paradox that the criterion on \chi^2 for testing a theory is much weaker than the criterion for finding…

High Energy Physics - Phenomenology · Physics 2007-05-23 J. C. Collins , J. Pumplin

We analyse the performance of twelve different implementations of Smoothed Particle Hydrodynamics (SPH) using seven tests designed to isolate key hydrodynamic elements of cosmological simulations which are known to cause the SPH algorithm…

Astrophysics · Physics 2009-10-30 R. J. Thacker , E. R. Tittley , F. R. Pearce , H. M. P. Couchman , P. A. Thomas

We review observational tests for the homogeneity of the Universe on large scales. Redshift and peculiar velocity surveys, radio sources, the X-Ray Background, the Lyman-$\alpha$ forest and the Cosmic Microwave Background are used to set…

Astrophysics · Physics 2007-05-23 Ofer Lahav

The central challenge in 21~cm cosmology is isolating the cosmological signal from bright foregrounds. Many separation techniques rely on the accurate knowledge of the sky and the instrumental response, including the antenna primary beam.…

The 21 cm spectral line emission of atomic neutral hydrogen (HI) is one of the primary wavelengths observed in radio astronomy. However, the signal is intrinsically faint and the HI content of galaxies depends on the cosmic environment,…

Instrumentation and Methods for Astrophysics · Physics 2023-02-08 J. A. Barkai , M. A. W. Verheijen , E. T. Martínez , M. H. F. Wilkinson

We explore the degeneracy and discreteness problems in the standard cosmological model (\Lambda CDM). We use the Observational Hubble Data (OHD) and the type Ia supernova (SNe Ia) data to study this issue. In order to describe the…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-16 Huan-Yu Teng , Yuan Huang , Tong-Jie Zhang

In materials science and many other application domains, 3D information can often only be extrapolated by taking 2D slices. In topological data analysis, persistence vineyards have emerged as a powerful tool to take into account topological…

Statistics Theory · Mathematics 2022-01-12 Alessandra Cipriani , Christian Hirsch , Martina Vittorietti

Modern optimizers such as AdamW, equipped with momentum and adaptive learning rate, are designed to escape local minima and explore the vast parameter space. This exploration is beneficial for finding good loss basins when training from…

Machine Learning · Computer Science 2024-11-05 Junjiao Tian , Chengyue Huang , Zsolt Kira
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