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In this work we use models of molecular clouds (MC), and non-LTE radiative transfer calculations, to obtain a theoretical calibration of the relation between LTE 13CO column density and true column density in MCs. The cloud models consist…

Astrophysics · Physics 2008-02-03 Paolo Padoan , Mika Juvela , John Bally , AAke Nordlund

Stein variational gradient descent (SVGD) is a kernel-based particle method for sampling from a target distribution, e.g., in generative modeling and Bayesian inference. SVGD does not require estimating the gradient of the log-density,…

Machine Learning · Statistics 2025-04-10 Viktor Stein , Wuchen Li

We adopt the deep learning method CASI-3D (Convolutional Approach to Structure Identification-3D) to infer the orientation of magnetic fields in sub-/trans- Alfvenic turbulent clouds from molecular line emission. We carry out…

Astrophysics of Galaxies · Physics 2023-01-25 Duo Xu , Chi-Yan Law , Jonathan C. Tan

Observations of translucent molecular gas in $^{12}$CO and $^{13}$CO emission lines, at high spectral and spatial resolutions, evidence different kinds of structures at small scales: (1) optically thin $^{12}$CO emission, (2) optically…

Astrophysics · Physics 2007-05-23 Pierre Hily-Blant , Jerome Pety , Edith Falgarone

We present numerical simulations of molecular clouds (MCs) with self-consistent CO gas-phase and isotope chemistry in various environments. The simulations are post-processed with a line radiative transfer code to obtain $^{12}$CO and…

Astrophysics of Galaxies · Physics 2016-04-25 László Szűcs , Simon C. O. Glover , Ralf S. Klessen

We analyze a technique of obtaining turbulence power spectrum using spectral line data along the velocity coordinate, which we refer to as Velocity Coordinate Spectrum (VCS). We formalize geometrical aspects of observation through a single…

Astrophysics · Physics 2007-05-23 A. Chepurnov , A. Lazarian

We investigate a mechanism for accelerating cool (10$^4$ K) clouds in the circumgalactic medium (CGM) with cosmic rays (CRs), possibly explaining some characteristics of observed high velocity clouds (HVCs). Enforcing CRs to stream down…

Astrophysics of Galaxies · Physics 2019-07-31 Joshua Wiener , Ellen G. Zweibel , Mateusz Ruszkowski

Magnetic fields and turbulence may play a key role in the evolution of protoclusters, influencing the formation of dense cores and stars. Here, we examine the morphology of the magnetic fields in the G327.29 protocluster using both the…

Granular gases are commonly characterized through their velocity distribution, which provides access to the granular temperature. In experiments, velocity distributions are typically obtained by particle tracking, which however becomes…

To characterize the absorption properties of this circumgalactic medium (CGM) and its relation to the LG we present the so-far largest survey of metal absorption in Galactic high-velocity clouds (HVCs) using archival ultraviolet (UV)…

We present fully-sampled maps of 461 GHz CO (4-3), 807 GHz CO (7-6), and 492 GHz [CI] (3P1-3P0) emission from the inner 3 degrees of the Galactic Center region taken with the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO)…

We describe a new method involving wavelet transforms for deriving the wind velocity associated with atmospheric turbulence layers from Generalized SCIDAR measurements. The algorithm analyses the cross-correlation of a series of…

Astrophysics · Physics 2016-08-30 B. Garcia-Lorenzo , J. J. Fuensalida

Gamma-Ray Bursts (GRBs) afterglows are rapidly decaying signals that pose significant detection challenges, requiring improved methods to track their temporal evolution. In this study, we systematically compare various techniques for…

High Energy Astrophysical Phenomena · Physics 2025-09-23 Léo Le Moigne , Mathieu de Bony de Lavergne , Armand Fiasson , Edna Ruiz-Velasco , David Sanchez , Kenta Terauchi

We describe a method to efficiently obtain two-dimensional velocity fields of distant, faint and small, emission-line galaxies with FORS2 at the VLT. They are examined for kinematic substructure to identify possible interaction processes.…

Dust polarization orientations in molecular clouds often tend to be close to tangential to the Stokes $I$ dust continuum emission contours. The magnetic field and the emission gradient orientations, therefore, show some correlation. A…

Astrophysics of Galaxies · Physics 2015-06-03 Patrick M. Koch , Ya-Wen Tang , Paul T. P. Ho

The analysis of data coming from interferometric antennas for gravitational waves detection may require a huge amount of computing power. The usual approach to the detection strategy is to set-up computer farms able to perform several tasks…

High Energy Physics - Experiment · Physics 2007-05-23 F. Acernese , F. Barone , R. De Rosa , R. Esposito , P. Mastroserio , L. Milano , S. Pardi , K. Qipiani , G. Spadaccini

We survey NV absorption in the afterglow spectra of long-duration gamma-ray bursts (GRBs) with the intent to study highly ionized gas in the galaxies hosting these events. We identify a high incidence (6/7) of spectra exhibiting NV gas with…

Recent studies provide evidence for the multi-scale nature of magnetic turbulence in the plasma sheet. Wavelet methods represent modern time series analysis techniques suitable for the description of statistical characteristics of…

Space Physics · Physics 2016-09-08 W. Baumjohann , R. Nakamura , A. Runov , M. Volwerk , T. L. Zhang , A. Balogh

We present a new constraint on the Galactic $^{12}$C/$^{13}$C gradient with sensitive HCO$^+$ absorption observations against strong continuum sources. The new measurements suffer less from beam dilution, optical depths, and chemical…

Astrophysics of Galaxies · Physics 2024-10-30 Gan Luo , Laura Colzi , Tie Liu , Thomas G. Bisbas , Di Li , Yichen Sun , Ningyu Tang