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We study the circumgalactic medium (CGM) of a z=0.54 simulated dwarf galaxy using hydroART simulations. We present our analysis methods, which emulate observations, including objective absorption line detection, apparent optical depth (AOD)…

The timeline of cosmic reionization remains uncertain despite sustained efforts to study how the ionizing output of early galaxies shaped the intergalactic medium (IGM). Using the semi-numerical code LIMFAST, we investigate the prospects…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-22 Guochao Sun , Adam Lidz , Tzu-Ching Chang , Jordan Mirocha , Steven R. Furlanetto

Entropic optimal transport problems are regularized versions of optimal transport problems. These models play an increasingly important role in machine learning and generative modelling. For finite spaces, these problems are commonly solved…

Machine Learning · Statistics 2025-12-30 O. Deniz Akyildiz , Pierre Del Moral , Joaquín Miguez

Foreground removal remains an ongoing challenge in radio cosmology, and increasingly sensitive experiments necessitate more robust analysis techniques. In this work, we model simulated data from a single-dish intensity mapping experiment,…

Instrumentation and Methods for Astrophysics · Physics 2026-04-30 Geoff G. Murphy , Philip Bull , Mario G. Santos , Zheng Zhang , Steven Cunnington

We report the detection of 21-cm absorption from foreground galaxies towards quasars, specifically z_gal = 0.3120 towards SDSS J084957.97+510829.0 (z_qso = 0.584; Pair-I) and z_gal = 0.3714 towards SDSS J144304.53+021419.3 (z_qso = 1.82;…

Astrophysics of Galaxies · Physics 2015-06-16 N. Gupta , R. Srianand , P. Noterdaeme , P. Petitjean , S. Muzahid

We present a new Fermi-LAT analysis of the Galactic-center excess (GCE) designed to substantially reduce the dominant systematic uncertainties associated with interstellar-emission and source modeling in the inner Galaxy. Using an optimized…

High Energy Astrophysical Phenomena · Physics 2026-05-29 Mattia Di Mauro

The sky-averaged cosmological 21 cm signal can improve our understanding of the evolution of the early Universe from the Dark Age to the end of the Epoch of Reionization. Although the EDGES experiment reported an absorption profile of this…

Instrumentation and Methods for Astrophysics · Physics 2023-12-05 O. A. Restrepo , F. I. Lucero , G. Chaparro , R. Rodríguez , F. Pizarro , R. Bustos , M. Díaz , F. P. Mena

Very Long Baseline Interferometry (VLBI) provides the highest-resolution radio intensity maps, crucial for detailed studies of compact sources like active galactic nuclei (AGN) and their relativistic jets. Analyzing jet components in these…

Instrumentation and Methods for Astrophysics · Physics 2025-10-02 Alfredo Amador-Portes , Eva Palafox , Víctor M. Patiño-Álvarez , Vahram Chavushyan , Andrei P. Lobanov , Sergio A. Dzib

We introduce a powerful semi-numeric modeling tool, 21cmFAST, designed to efficiently simulate the cosmological 21-cm signal. Our code generates 3D realizations of evolved density, ionization, peculiar velocity, and spin temperature fields,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Andrei Mesinger , Steven Furlanetto , Renyue Cen

[abridged] Aims. The aim of the present paper is to provide new and more detailed relations at the kpc scale between the gas surface density and the face-on optical depth directly calibrated on galaxies, in order to compute the attenuation…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 M. Boquien , A. Boselli , V. Buat , M. Baes , G. Bendo , S. Boissier , L. Ciesla , A. Cooray , L. Cortese , S. Eales , J. Koda , V. Lebouteiller , I. de Looze , M. W. L. Smith , L. Spinoglio , C. D. Wilson

A key challenge in spatial statistics is the analysis for massive spatially-referenced data sets. Such analyses often proceed from Gaussian process specifications that can produce rich and robust inference, but involve dense covariance…

Methodology · Statistics 2019-07-25 Shinichiro Shirota , Andrew O. Finley , Bruce D. Cook , Sudipto Banerjee

We report a $\approx 400$-hour Giant Metrewave Radio Telescope (GMRT) search for HI 21 cm emission from star-forming galaxies at $z = 1.18-1.39$ in seven fields of the DEEP2 Galaxy Survey. Including data from an earlier 60-hour GMRT…

Astrophysics of Galaxies · Physics 2021-06-09 Aditya Chowdhury , Nissim Kanekar , Barnali Das , K. S. Dwarakanath , Shiv Sethi

We present the first full map of the H-alpha emission from the intermediate-velocity cloud Complex L. Kinematically resolved emission components from the ionized gas reveal a close spatial and velocity correspondence to that of the neutral…

Astrophysics · Physics 2014-10-13 L. M. Haffner

We describe an automated search through the Leiden/Dwingeloo HI Survey (LDS) for high-velocity clouds north of Dec=-28 deg. From the general catalog we extract a sample of isolated high-velocity clouds, CHVCs: anomalous-velocity HI clouds…

Astrophysics · Physics 2009-11-07 V. de Heij , R. Braun , W. B. Burton

Many catalogues of isolated compact groups of galaxies (CGs) have been extracted using Hickson's criteria to identify isolated, dense systems of galaxies, with at least three or four galaxies concordant in magnitude and redshift. But is not…

Astrophysics of Galaxies · Physics 2022-02-09 Antonela Taverna , Eugenia Diaz-Gimenez , Ariel Zandivarez , Gary Mamon

We present a new method for fitting simple hydrodynamical models to the (l,v) distribution of atomic and molecular gas observed in the Milky Way. The method works by matching features found in models and observations. It is based on the…

Astrophysics of Galaxies · Physics 2015-06-23 Mattia C. Sormani , John Magorrian

Recent advancements in remote sensing technology and the increasing size of satellite constellations allows massive geophysical information to be gathered daily on a global scale by numerous platforms of different fidelity. The…

Computation · Statistics 2021-05-11 Si Cheng , Bledar A. Konomi , Jessica L. Matthews , Georgios Karagiannis , Emily L. Kang

Cross-correlating neutral hydrogen (HI) 21cm intensity mapping with galaxy surveys provides an effective probe of astrophysical and cosmological information. This work presents a cross-correlation analysis between MeerKAT single-dish HI…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-12 Yu-Er Jiang , Yan Gong , Qi Xiong , Wenxiang Pei , Yun Liu , Furen Deng , Zi-yan Yuwen , Meng Zhang , Xingchen Zhou , Xuelei Chen , Yin-Zhe Ma , Qi Guo , Bin Yue

We present new results of a spectroscopic survey of circumstellar HI in the direction of evolved stars made with the Nancay Radiotelescope. The HI line at 21 cm has been detected in the circumstellar shells of a variety of evolved stars:…

Astrophysics · Physics 2018-05-02 Gerard , Le Bertre

The precise form of the foregrounds for sky-averaged measurements of the 21-cm line during and before the epoch of reionization is unknown. We suggest that the level of complexity in the foreground models used to fit global 21-cm data…

Cosmology and Nongalactic Astrophysics · Physics 2015-02-26 Geraint Harker