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The 21-cm emission from atomic hydrogen (HI) is one of the most important tracers of the structure and dynamics of the interstellar medium. Thanks to Galactic rotation, the line is Doppler shifted and, assuming a model for the velocity…

Astrophysics of Galaxies · Physics 2023-05-26 Philipp Mertsch , Vo Hong Minh Phan

The spatial distribution of the gaseous components of the Milky Way is of great importance for a number of different fields, for example, Galactic structure, star formation, and cosmic rays. However, obtaining distance information to…

This paper presents a statistical explanation of filament formation in the galactic atomic hydrogen. Recently developed technique allows to determine the 3D spectrum of random HI density. We claim that even in the absence of dynamical…

Astrophysics · Physics 2009-10-28 Alex Lazarian , Dmitri Pogosyan

Galaxies in the early Universe were more compact and contained more molecular gas than today. In this paper, we revisit the relation between these empirical findings, and we quantitatively predict the cosmic evolution of the surface…

Cosmology and Nongalactic Astrophysics · Physics 2012-02-09 Danail Obreschkow , Steve Rawlings

Using a simple model of photodissociated atomic hydrogen on a galactic scale, it is possible to derive total hydrogen volume densities. These densities, obtained through a combination of atomic hydrogen, far-ultraviolet and metallicity…

Astrophysics of Galaxies · Physics 2015-06-11 J. S. Heiner , J. R. Sánchez-Gallego , L. Rousseau-Nepton , J. H. Knapen

We present a new model of the three-dimensional distribution of molecular gas in the Milky Way Galaxy, based on CO line data. Our analysis is based on a gas-flow simulation of the inner Galaxy using smoothed-particle hydrodynamics (SPH)…

Astrophysics · Physics 2009-06-23 Martin Pohl , Peter Englmaier , Nicolai Bissantz

Direct measurements of cosmic ray (CR) species combined with observations of their associated gamma-ray emissions can be used to constrain models of CR propagation, trace the structure of the Galaxy, and search for signatures of new…

High Energy Astrophysical Phenomena · Physics 2018-04-11 Gudlaugur Johannesson , Troy A. Porter , Igor V. Moskalenko

Carbon monoxide (CO) is the best tracer of Galactic molecular hydrogen (H2). Its lowest rotational emission lines are in the radio regime and thanks to Galactic rotation emission at different distances is Doppler shifted. For a given gas…

Astrophysics of Galaxies · Physics 2023-01-06 Philipp Mertsch , Andrea Vittino

We consider the consequences of applying general relativity to the description of the dynamics of a galaxy, given the observed flattened rotation curves. The galaxy is modeled as a stationary axially symmetric pressure-free fluid. In spite…

Astrophysics · Physics 2010-10-27 F. I. Cooperstock , S. Tieu

In this work we present the first non-linear, non-Gaussian full Bayesian large scale structure analysis of the cosmic density field conducted so far. The density inference is based on the Sloan Digital Sky Survey data release 7, which…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 J. Jasche , F. S. Kitaura , C. Li , T. A. Ensslin

Stars form in cold molecular clouds. However, molecular gas is difficult to observe because the most abundant molecule (H2) lacks a permanent dipole moment. Rotational transitions of CO are often used as a tracer of H2, but CO is much less…

We derive radial and vertical distributions of HI and H2 gas densities in our Galaxy by using the terminal velocity method. We calculate the molecular fraction (f_mol) defined as the ratio of the molecular hydrogen to total hydrogen gas…

Astrophysics · Physics 2007-05-23 K. Imamura , Y. Sofue

We present a multi-scale analysis of molecular hydrogen in a Milky Way-like simulated galaxy. Our census covers the gas content of the entire disc, to radial profiles and the Kennicutt-Schmidt relation, to a study of its molecular clouds,…

Astrophysics of Galaxies · Physics 2019-01-16 Sarah Nickerson , Romain Teyssier , Joakim Rosdahl

We infer the gravitational potential of the Galactic disk by analysing the phase-space densities of 120 stellar samples in 40 spatially separate sub-regions of the solar neighbourhood, using Gaia's second data release (DR2), in order to…

Astrophysics of Galaxies · Physics 2021-02-10 Axel Widmark , Pablo Fernández de Salas , Giacomo Monari

We present a fully probabilistic, physical model of the non-linearly evolved density field, as probed by realistic galaxy surveys. Our model is valid in the linear and mildly non-linear regimes and uses second order Lagrangian perturbation…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Jens Jasche , Benjamin D. Wandelt

We present a non-parametric model for inferring the three-dimensional (3D) distribution of dust density in the Milky Way. Our approach uses the extinction measured towards stars at different locations in the Galaxy at approximately known…

Astrophysics of Galaxies · Physics 2017-03-22 S. Rezaei Kh. , C. A. L. Bailer-Jones , R. J. Hanson , M. Fouesneau

The major uncertainties in studies of the multi-scale structure of the Universe arise not from observational errors but from the variety of legitimate definitions and detection methods for individual structures. To facilitate the study of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 M. J. Way , P. R. Gazis , Jeffrey D. Scargle

Here I present results from individual galaxy studies and galaxy surveys in the Local Universe with particular emphasis on the spatially resolved properties of neutral hydrogen gas. The 3D nature of the data allows detailed studies of the…

Astrophysics of Galaxies · Physics 2020-02-19 B. S. Koribalski

We investigate the atomic (HI) and molecular (H_2) Hydrogen content of normal galaxies by combining observational studies linking galaxy stellar and gas budgets to their host dark matter (DM) properties, with a physically grounded galaxy…

Astrophysics of Galaxies · Physics 2010-05-25 M. Cook , C. Evoli , E. Barausse , G. L. Granato , A. Lapi

We present a novel Bayesian method, referred to as Blobby3D, to infer gas kinematics that mitigates the effects of beam smearing for observations using Integral Field Spectroscopy (IFS). The method is robust for regularly rotating galaxies…

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