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We present observations of a new group of structures in the diffuse Galactic ISM: slender, linear HI features we dub "fibers" that extend for many degrees at high Galactic latitude. To characterize and measure the extent and strength of…

Astrophysics of Galaxies · Physics 2014-06-19 S E Clark , J E G Peek , M E Putman

A number of current and future experiments aim to detect the reionization of neutral hydrogen by the first stars and galaxies in the Universe via the redshifted 21cm line. Using the \textsc{BlueTides} simulation, we investigate the…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-20 James E Davies , Rupert A. Croft , Tiziana Di-Matteo , Bradley Greig , Yu Feng , Stuart Wyithe

We present a 21cm line HI self-absorption (HISA) survey of cold atomic gas within Galactic longitudes 75 to 146 degrees and latitudes -3 to +5 degrees. We identify HISA as spatially and spectrally confined dark HI features and extract it…

The rapid development of large climate models has created the requirement of storing and transferring massive atmospheric data worldwide. Therefore, data compression is essential for meteorological research, but an efficient compression…

Machine Learning · Computer Science 2024-11-12 Zhewen Xu , Baoxiang Pan , Hongliang Li , Xiaohui Wei

We investigate the 21-cm signature that may arise from the intergalactic medium (IGM) prior to the epoch of full reionization (z>5). In scenarios in which the IGM is reionized by discrete sources of photoionizing radiation, the neutral gas…

Astrophysics · Physics 2009-10-28 Piero Madau , Avery Meiksin , Martin J. Rees

Following an established protocol of science, that results must be reproducible, we examine the Gaussian fits to Galactic 21-cm emission profiles obtained by two seemingly complementary methods: the semi-automated approach based on the…

Astrophysics of Galaxies · Physics 2020-04-21 G. L. Verschuur , J. T. Schmelz

In studying the interstellar medium (ISM) and Galactic cosmic rays (CRs), uncertainty of the interstellar gas density has always been an issue. To overcome this difficulty, we used a component decomposition of the 21-cm HI line emission and…

High Energy Astrophysical Phenomena · Physics 2022-08-31 T. Mizuno , K. Hayashi , J. Metzger , I. V. Moskalenko , E. Orlando , A. W. Strong , H. Yamamoto

(abridged) Spectroscopic observations of high-redshift galaxies slowly reveal the same complexity of the interstellar medium (ISM) as expected from resolved observations in nearby galaxies. While providing a wealth of diagnostics, such…

Astrophysics of Galaxies · Physics 2022-11-09 Vianney Lebouteiller , Lise Ramambason

Context: To investigate the properties of the 21-cm radio-lines of galactic neutral hydrogen, the profiles of "The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI" are decomposed into Gaussian components. Aims: The width distribution of…

Astrophysics · Physics 2008-11-26 Urmas Haud , Peter M. W. Kalberla

An accurate estimate of the interstellar gas density distribution is crucial to understanding the interstellar medium (ISM) and Galactic cosmic rays (CRs). To comprehend the ISM and CRs in a local environment, a study of the diffuse…

High Energy Astrophysical Phenomena · Physics 2020-02-26 T. Mizuno , S. Abdollahi , Y. Fukui , K. Hayashi , T. Koyama , A. Okumura , H. Tajima , H. Yamamoto

We report statistically significant detection of H I 21-cm emission from intermediate-redshift ($z\approx0.2$-0.6) galaxies. By leveraging multi-sightline galaxy survey data from the Cosmic Ultraviolet Baryon Survey (CUBS) and deep radio…

We extend the results of previous analyses towards constraining the abundance and clustering of post-reionization ($z \sim 0-5$) neutral hydrogen (HI) systems using a halo model framework. We work with a comprehensive HI dataset including…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-23 Hamsa Padmanabhan , Alexandre Refregier , Adam Amara

The 21-cm brightness-temperature field of neutral hydrogen during the Epoch of Reionization and Cosmic Dawn is a rich source of cosmological and astrophysical information, primarily due to its significant non-Gaussian features. However, the…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-12 Bohdan Bidenko , Léon V. E. Koopmans , P. Daniel Meerburg

We present synthetic Hi and CO observations of a simulation of decaying turbulence in the thermally bistable neutral medium. We first present the simulation, with clouds initially consisting of clustered clumps. Self-gravity causes these…

Astrophysics of Galaxies · Physics 2015-08-06 Jonathan S. Heiner , Enrique Vázquez-Semadeni , Javier Ballesteros-Paredes

Simulating the distribution of cosmological neutral hydrogen (HI) during the epoch of reionization requires a high dynamic range and is hence computationally expensive. The size of the simulation is dictated by the largest scales one aims…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-24 Ankur Barsode , Tirthankar Roy Choudhury

Unraveling the multi-phase structure of the diffuse interstellar medium (ISM) as traced by neutral hydrogen (HI) is essential to understanding the lifecycle of the Milky Way. However, HI phase separation is a challenging and…

Astrophysics of Galaxies · Physics 2025-10-16 Minjie Lei , S. E. Clark , Rudy Morel , E. Allys , Iryna S. Butsky , Caleb Redshaw , Drummond B. Fielding

Hyperspectral remote sensing images (HSIs) are characterized by having a low spatial resolution and a high spectral resolution, whereas multispectral images (MSIs) are characterized by low spectral and high spatial resolutions. These…

Computer Vision and Pattern Recognition · Computer Science 2014-06-11 Miguel Simões , José Bioucas-Dias , Luis B. Almeida , Jocelyn Chanussot

We present a new method which constructs an HI super-profile of a galaxy which is based on profile decomposition analysis. The decomposed velocity profiles of an HI data cube with an optimal number of Gaussian components are co-added after…

Astrophysics of Galaxies · Physics 2022-11-07 Minsu Kim , Se-Heon Oh

Hyperspectral images (HSIs) are inevitably degraded by a mixture of various types of noise, such as Gaussian noise, impulse noise, stripe noise, and dead pixels, which greatly limits the subsequent applications. Although various denoising…

Image and Video Processing · Electrical Eng. & Systems 2024-01-12 Dongyi Li , Dong Chu , Xiaobin Guan , Wei He , Huanfeng Shen

Optimization problems arise in a range of scenarios, from optimal control to model parameter estimation. In many applications, such as the development of digital twins, it is essential to solve these optimization problems within…

Optimization and Control · Mathematics 2025-09-01 Joseph Hart , Shane A. McQuarrie , Zachary Morrow , Bart van Bloemen Waanders