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Low-frequency radio observations of neutral hydrogen during and before the epoch of cosmic reionization will provide ~ 1000 quasi-independent source planes, each of precisely known redshift, if a resolution of ~1 arcminutes or better can be…

Astrophysics · Physics 2017-03-15 R. Benton Metcalf , S. D. M. White

We have investigated the time scale for formation of molecular clouds by examining the conversion of HI to H2 using a time-dependent model. H2 formation on dust grains and cosmic ray and photo destruction are included in one-dimensional…

Astrophysics · Physics 2008-11-26 Paul F. Goldsmith , Di Li , Marko Krco

We describe a combined halo model to constrain the distribution of neutral hydrogen (HI) in the post-reionization universe. We combine constraints from the various probes of HI at different redshifts: the low-redshift 21-cm emission line…

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

Galaxy disks are shown to contain a significant population of atomic clouds of 100pc linear size which are self-opaque in the 21cm transition. These objects have HI column densities as high as 10^23 and contribute to a global opacity…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Robert Braun

The 21 cm hyperfine transition of the atomic hydrogen (HI) in ground state is a powerful probe of the neutral gas content of the universe. This radio frequency transition has been used routinely for decades to observe, both in emission and…

Astrophysics of Galaxies · Physics 2019-11-26 Preetha Saha , Nirupam Roy , Mukul Bhattacharya

Clouds in optical satellite images are a major concern since their presence hinders the ability to carry accurate analysis as well as processing. Presence of clouds also affects the image tasking schedule and results in wastage of valuable…

Computer Vision and Pattern Recognition · Computer Science 2023-12-04 Subhajit Paul , Ashutosh Gupta

Precision cosmology requires accurate galaxy redshifts, but next generation optical surveys will observe unprecedented numbers of resolved galaxies, placing strain on the amount of spectroscopic follow-up required. We show how useful…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-07 Steven Cunnington , Ian Harrison , Alkistis Pourtsidou , David Bacon

We construct a simple but self-consistent analytic ionization model for rapid exploration of 21cm power spectrum observables in redshift space. It is fully described by the average ionization fraction $x_e(z)$ and HII patch size $R(z)$ and…

Astrophysics · Physics 2009-11-13 Xiaomin Wang , Wayne Hu

Upcoming galaxy surveys with the SKA Observatory will detect neutral hydrogen (HI) across unprecedented volumes, and their scientific return will crucially depend on predictive models for HI observables. In this work, we present a framework…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-25 Joël Mayor , Marta Spinelli , Gabriella De Lucia , Robert Yates , Alexandre Refregier , Fabio Fontanot , Lizhi Xie , Michaela Hirschmann

In the Halo21 absorption modeling challenge we generated synthetic absorption spectra of the circumgalactic medium (CGM), and attempted to estimate the metallicity, temperature, and density (Z, T, and nH) of the underlying gas using…

High-resolution JWST-MIRI images now allow us to resolve in great detail the multi-scale nature of the emission in nearby star-forming galaxies, from compact star-forming regions to large-scale diffuse emission, giving new insights into…

We present a high resolution (FWHM=2.7 km/s), high S/N echelle spectrum for the z = 2.26 QSO J2123-0050 and determine elemental abundances for the z = 2.06 sub-DLA in its line of sight. This high redshift sub-DLA has a complex kinematic…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Nikola Milutinovic , Sara L. Ellison , J. Xavier Prochaska , Jason Tumlinson

We model the distribution of neutral hydrogen (HI) in the post-reionization era and investigate its detectability in 21 cm intensity mapping with the future SKA radio telescope. We rely on high resolution hydrodynamical N-body simulations.…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Francisco Villaescusa-Navarro , Matteo Viel , Kanan K. Datta , T. Roy Choudhury

We present a pilot HI survey of 17 Planck Galactic Cold Clumps (PGCCs) with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). HI Narrow Self-Absorption (HINSA) is an effective method to detect cold HI being mixed with…

We present simulated observations of gas kinematics in galaxies formed in 10 pc resolution cosmological simulations with the hydrodynamical + N-body code RAMSES, using the new RAMSES2HSIM pipeline with the simulated observing pipeline…

Instrumentation and Methods for Astrophysics · Physics 2020-09-11 Mark L. A. Richardson , Laurence Routledge , Niranjan Thatte , Matthias. Tecza , Ryan C. W. Houghton , Miguel Pereira-Santaella , Dimitra Rigopoulou

The ionisation structure of the Intergalactic Medium (IGM) during reionisation is sensitive to the unknown galaxy formation physics that prevailed at that time. This structure introduces non-Gaussian statistics into the redshifted 21 cm…

Cosmology and Nongalactic Astrophysics · Physics 2015-01-20 Stuart Wyithe , Paul M. Geil , Hansik Kim

We present a new model for computing consistently the line and continuum emission from galaxies, based on a combination of recent population synthesis and photoionization codes. We use effective parameters to describe the HII regions and…

Astrophysics · Physics 2015-06-24 S. Charlot , M. Longhetti

The 21-cm intensity mapping (IM) of neutral hydrogen (HI) is a promising tool to probe the large-scale structures. Sky maps of 21-cm intensities can be highly contaminated by different foregrounds, such as Galactic synchrotron radiation,…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-01 Elimboto Yohana , Yin-Zhe Ma , Di Li , Xuelei Chen , Wei-Ming Dai

In remote sensing applications, such as disaster detection and response, real-time efficiency and model lightweighting are of critical importance. Consequently, existing remote sensing image super-resolution methods often face a trade-off…

Computer Vision and Pattern Recognition · Computer Science 2025-12-02 Yi Liu , Yi Wan , Xinyi Liu , Qiong Wu , Panwang Xia , Xuejun Huang , Yongjun Zhang

The spatial distribution of neutral hydrogen (HI) in the Universe contains a wealth of cosmological information. The 21 cm emission line can be used to map the HI up to very high redshift and therefore reveal us something about the…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-09 Emanuele Castorina , Francisco Villaescusa-Navarro