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We present full modeling of tangent point emission of HI as seen in the 21 cm transition in the inner Galaxy ($R \simeq 3-8 \kpc$). The model used takes into account emission from a large path length along the line of sight, corresponding…

Astrophysics · Physics 2011-03-28 Sangeeta Malhotra

Context. Gas within a galaxy is forced to establish pressure balance against gravitational forces. The shape of an unperturbed gaseous disk can be used to constrain dark matter models. Aims. We derive the 3-D HI volume density distribution…

Astrophysics · Physics 2009-11-13 P. M. W. Kalberla , L. Dedes , J. Kerp , U. Haud

We examine the dependence between hydrogen total mass $M_{HI}$ and rotation speed $V_{rot}$, optical size $D_{25}$ or disc radial scale $R_0$ for two samples of late-type galaxies: a) isolated galaxy (AMIGA sample), and b) the edge-on…

Astrophysics of Galaxies · Physics 2017-07-26 Analoty V. Zasov , Natalia A. Zaitseva

Over the past two decades observations have revealed that the vertical density distribution of stars in galaxies near the mid-plane is substantially steeper than the sech^2 function that is expected from an isothermal approximation.…

Astrophysics · Physics 2011-02-11 Arunima Banerjee , Chanda J. Jog

We use an empirical relation to measure the HI scale height of relatively HI rich galaxies using 21-cm observations. The galaxies were selected from the BLUEDISK, THINGS and VIVA surveys. We aim to compare the thickness of the HI layer of…

Astrophysics of Galaxies · Physics 2021-05-25 Toky H. Randriamampandry , Jing Wang , K. Moses Mogotsi

Due to our vantage point in the disk of the Galaxy, its 3D structure is not directly accessible. However, knowing the spatial distribution, e.g. of atomic and molecular hydrogen gas is of great importance for interpreting and modelling…

Astrophysics of Galaxies · Physics 2023-09-26 Laurin Söding , Philipp Mertsch , Vo Hong Minh Phan

The neutral hydrogen line profiles along the major axis of the nearby spiral galaxy NGC 2403 show a wing towards the sytemic velocity. This asymmetry can be explained with the presence of an abnormally thick HI disk (FWHM ~ 5 kpc) or with a…

Astrophysics · Physics 2007-05-23 W. E. Schaap , R. Sancisi , R. A. Swaters

We derived the three-dimensional distribution of HI gas in the Milky Way Galaxy using the latest HI survey data cubes and rotation curves. The distance of the HI gas was determined by the kinematic distance using a rotation curve. We solved…

Astrophysics · Physics 2015-06-24 Hiroyuki Nakanishi , Yoshiaki Sofue

We present a study of the filamentary structure in the atomic hydrogen (HI) emission at the 21 cm wavelength toward the Galactic plane using the observations in the HI4PI survey. Using the Hessian matrix method across radial velocity…

New deep VLA D array HI observations of the highly inclined nearby spiral galaxy NGC 2683 are presented. Archival C array data were processed and added to the new observations. To investigate the 3D structure of the atomic gas disk, we made…

Astrophysics of Galaxies · Physics 2016-02-17 B. Vollmer , F. Nehlig , R. Ibata

From the analysis of sensitive HI 21-cm line observations, we find evidence for vertically extended HI emission (|z|<~2.4 kpc) in the edge-on, low surface brightness spiral galaxy UGC7321. Three-dimensional modelling suggests that the HI…

Astrophysics · Physics 2009-11-07 L. D. Matthews , Kenneth Wood

Could the velocity spread, increasing with time, in the Galactic disk be explained as a result of gravitational interactions of stars with giant molecular clouds (GMCs) and spiral arms? Do the old open clusters high above the Galactic plane…

Astrophysics of Galaxies · Physics 2016-09-28 Bengt Gustafsson , Ross Church , Melvyn B. Davies , Hans Rickman

Empirical studies of the relationship between baryonic matter in galaxies and the gravitational potential of their host halos are important to constrain our theoretical framework for galaxy formation and evolution. One such relation,…

Astrophysics of Galaxies · Physics 2024-04-04 Manasvee Saraf , Luca Cortese , O. Ivy Wong , Barbara Catinella , Steven Janowiecki , Jennifer A. Hardwick

Assuming a vertical hydrostatic equilibrium in the baryonic discs, joint Poisson's-Boltzmann equation was set up and solved numerically in a sample of 23 nearby dwarf galaxies from the LITTLE-THINGS survey. This is the largest sample to…

Astrophysics of Galaxies · Physics 2020-05-14 Narendra Nath Patra

High resolution, multi-wavelength maps of a sizeable set of nearby galaxies have made it possible to study how the surface densities of HI, H2 and star formation rate (Sigma_HI, Sigma_H2, Sigma_SFR) relate on scales of a few hundred…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 F. Bigiel , A. Leroy , F. Walter

Aims: we studied the global distribution and kinematics of the extra-planar neutral gas in the Milky Way. Methods: we built 3D models for a series of Galactic HI layers, projected them for an inside view, and compared them with the…

Astrophysics of Galaxies · Physics 2015-05-20 Antonino Marasco , Filippo Fraternali

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…

The HRS is a complete volume-limited sample of nearby objects including Virgo cluster and isolated objects. Using a recent compilation of HI and CO data we study the effects of the cluster on the molecular gas content of spiral galaxies. We…

Astrophysics of Galaxies · Physics 2015-06-18 A. Boselli , L. Cortese , M. Boquien , S. Boissier , B. Catinella , G. Gavazzi , C. Lagos , A. Saintonge

We present the germ of a new model for High Velocity Clouds, derived from the idea that the dark matter halo of our Galaxy is in the form of cold, planetary-mass gas clouds. In this picture HVCs arise as a result of disruptive collisions…

Astrophysics · Physics 2007-05-23 Mark Walker , Mark Wardle

A new model for three dimensional distribution of atomic hydrogen gas in the Milky Way is derived using the 21cm LAB survey data. The global features of the gas distribution such as spiral arms are reproduced. The Galactic plane warps…

Astrophysics of Galaxies · Physics 2012-07-27 Maryam Tavakoli