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This work deals with a novel Gaussian filter-based pressure correction technique with a super compact higher order finite difference scheme for solving unsteady three-dimensional (3D) incompressible, viscous flows. This pressure correction…

Numerical Analysis · Mathematics 2024-07-30 Ashwani Punia , Rajendra K. Ray

Spatial statistics often rely on Gaussian processes (GPs) to capture dependencies across locations. However, their computational cost increases rapidly with the number of locations, potentially needing multiple hours even for moderate…

Computation · Statistics 2025-10-23 Sébastien Garneau , Carlos T. P. Zanini , Alexandra M. Schmidt

Radio-interferometric arrays require very precise calibration to detect the Epoch of Reionization 21-cm signal. A remarkably complete and accurate sky model is therefore needed in the patches of the sky used to perform the calibration.…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-13 Khandakar Md Asif Elahi , Samir Choudhuri , Nirupam Roy , Md Rashid , Philip Bull , Dharam Vir Lal

We present a study exploring the nature and properties of the Circum-Galactic Medium (CGM) and its connection to the atomic gas content in the interstellar medium (ISM) of galaxies as traced by the HI 21cm line. Our sample includes 45 low-z…

Interloper contamination due to line misidentification is an important issue in the future low-resolution spectroscopic surveys. We realize that the algorithm previously used for photometric redshift self-calibration, with minor…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-28 Hui Peng , Yu Yu

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

Intervening HI 21-cm absorption systems at z > 1.0 are very rare and only 4 confirmed detections have been reported in the literature. Despite their scarcity, they provide interesting and unique insights into the physical conditions in the…

Astrophysics · Physics 2009-05-29 Neeraj Gupta , R. Srianand , P. Petitjean , P. Khare , D. J. Saikia , D. G. York

Characterizing the structure of the Galactic interstellar medium (ISM) in three dimensions is of high importance for accurate modeling of dust emission as a foreground to the Cosmic Microwave Background (CMB). At high Galactic latitude,…

Astrophysics of Galaxies · Physics 2020-10-22 G. V. Panopoulou , D. Lenz

We report the first results of a programme aimed at studying the properties of high redshift galaxies with on-going massive and dominant episodes of star formation (HII galaxies). We use the $L(\mathrm{H}\beta) - \sigma$ distance estimator…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Roberto Terlevich , Elena Terlevich , Jorge Melnick , Ricardo Chávez , Manolis Plionis , Fabio Bresolin , Spyros Basilakos

Interstellar neutral hydrogen (HI) emission spectra manifest several families of linewidths whose numerical values (34, 13 & 6 km/s) appear to be related to the critical ionization velocities (CIVs) of the most abundant interstellar atomic…

Astrophysics · Physics 2009-11-13 Gerrit L. Verschuur

Using the latest upper limits on the 21-cm power spectrum at $z\approx9.1$ from the Low Frequency Array (LOFAR), we explore regions of parameter space which are inconsistent with the data. We use 21CMMC, a Monte Carlo Markov Chain sampler…

We address the inverse problem of cosmic large-scale structure reconstruction from a Bayesian perspective. For a linear data model, a number of known and novel reconstruction schemes, which differ in terms of the underlying signal prior,…

Astrophysics · Physics 2009-11-06 F. S. Kitaura , T. A. Ensslin

We model the distribution of the observed profiles of 21 cm line emission from neutral hydrogen (HI) in central galaxies selected from a statistically representative mock catalog of the local Universe in the Lambda-cold dark matter…

Astrophysics of Galaxies · Physics 2021-05-12 Aseem Paranjape , R. Srianand , Tirthankar Roy Choudhury , Ravi K. Sheth

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…

Data analysis and interpretation often relies on an approximation of an empirical dataset by some analytic functions or models. Actual implementations usually rely on a non-linear multi-dimensional optimization algorithm, typically…

Instrumentation and Methods for Astrophysics · Physics 2025-01-29 Igor Chilingarian , Kirill Grishin

Mapping the unresolved intensity of the 21-cm emission of neutral hydrogen (HI) is now regarded as one the most promising tools for cosmological investigation in the coming decades. Here, we investigate, for the first time, extensions of…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-05 Stefano Camera , Hamsa Padmanabhan

We have processed the data accumulated with INTEGRAL SPI during 4 years (~ 51 Ms) to study the Galactic ``diffuse'' emission morphology in the 20 keV to 8 MeV energy range. To achieve this objective, we have derived simultaneously an…

Astrophysics · Physics 2009-11-13 L. Bouchet , E. Jourdain , J. P. Roques , A. Strong , R. Diehl , F. Lebrun , R. Terrier

Upcoming 21-cm intensity surveys will use the hyperfine transition in emission to map out neutral hydrogen in large volumes of the universe. Unfortunately, large spatial scales are completely contaminated with spectrally smooth…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-27 Chirag Modi , Martin White , Anze Slosar , Emanuele Castorina

In two recent publications [Kov{\'a}cs, Larsson, and Mesforush, SIAM J. Numer. Anal. 49(6), 2407-2429, 2011] and [Furihata, et al., SIAM J. Numer. Anal. 56(2), 708-731, 2018], strong convergence of the semi-discrete and fully discrete…

Numerical Analysis · Mathematics 2020-06-16 Ruisheng Qi , Xiaojie Wang

We present 21-cm Spectral Line Observations of Neutral Gas with the VLA (21-SPONGE), a Karl G. Jansky Very Large Array (VLA) large project (~600 hours) for measuring the physical properties of Galactic neutral hydrogen (HI). 21-SPONGE is…

Astrophysics of Galaxies · Physics 2018-10-10 Claire E. Murray , Snezana Stanimirovic , W. M. Goss , Carl Heiles , John M. Dickey , Brian Babler , Chang-Goo Kim
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