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In a sample of local active galactic nuclei studied at a spatial resolution on the order of 10 pc we show that the interstellar medium traced by the molecular hydrogen v=1-0 S(1) 2.1um line forms a geometrically thick, clumpy disk. The…

Astrophysics of Galaxies · Physics 2011-02-11 E. K. S. Hicks , R. I. Davies , M. A. Malkan , R. Genzel , L. J. Tacconi , F. Muller Sanchez , A. Sternberg

I model the multi-phase interstellar medium (ISM) randomly heated and shocked by supernovae, with gravity, differential rotation and other parameters we understand to be typical of the solar neighbourhood. The simulations are 3D extending…

Astrophysics of Galaxies · Physics 2017-12-15 Frederick Gent

The diffuse ionized gas (DIG) is an important component of the interstellar medium that can provide insights into the different physical processes affecting the gas in galaxies. We utilise optical IFU observations of 71 gas-stripped and…

Our aim is to explore the relation between gas, atomic and molecular, and dust in spiral galaxies. Gas surface densities are from atomic hydrogen and CO line emission maps. To estimate the dust content, we use the disk opacity as inferred…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 B. W. Holwerda , R. J. Allen , W. J. G. de Blok , A. Bouchard , R. A. Gonzalez-Lopezlira , P. C. van der Kruit , A. Leroy

Using over a million and a half extragalactic spectra we study the properties of the mysterious Diffuse Interstellar Bands (DIBs) in the Milky Way. These data provide us with an unprecedented sampling of the skies at high Galactic-latitude…

Astrophysics of Galaxies · Physics 2015-06-22 Dalya Baron , Dovi Poznanski , Darach Watson , Yushu Yao , J. Xavier Prochaska

The probability density function (PDF) of velocity fluctuations is studied experimentally for grid turbulence in a systematical manner. At small distances from the grid, where the turbulence is still developing, the PDF is sub-Gaussian. At…

Fluid Dynamics · Physics 2009-11-07 H. Mouri , M. Takaoka , A. Hori , Y. Kawashima

Using self-gravitational hydrodynamical numerical simulations, we investigated the evolution of high-density turbulent molecular clouds swept by a colliding flow. The interaction of shock waves due to turbulence produces networks of thin…

Solar and Stellar Astrophysics · Physics 2015-06-23 Tomoaki Matsumoto , Kazuhito Dobashi , Tomomi Shimoikura

We explore the structure and statistics of multiphase, magnetized ISM turbulence in the local Milky Way by means of driven periodic box numerical MHD simulations. Using the higher order-accurate piecewise-parabolic method on a local stencil…

Astrophysics of Galaxies · Physics 2017-06-19 Alexei G. Kritsuk , Sergey D. Ustyugov , Michael L. Norman

We study the probability distribution function (PDF) of mass surface densities, $\Sigma$, of infrared dark cloud (IRDC) G028.37+00.07 and its surrounding giant molecular cloud. This PDF constrains the physical processes, such as turbulence,…

Astrophysics of Galaxies · Physics 2016-09-23 Wanggi Lim , Jonathan C. Tan , Jouni Kainulainen , Bo Ma , Michael J. Butler

Probability distribution functions (PDFs) of column densities are an established tool to characterize the evolutionary state of interstellar clouds. Using simulations, we show to what degree their determination is affected by noise,…

Instrumentation and Methods for Astrophysics · Physics 2016-05-25 Volker Ossenkopf-Okada , Timea Csengeri , Nicola Schneider , Christoph Federrath , Ralf S. Klessen

The opacity of spiral galaxy disks, from counts of distant galaxies, is compared to HI column densities. The opacity measurements are calibrated using the ``Synthetic Field Method'' from Gonzalez et al (1998) and Holwerda et al. (2005a).…

Astrophysics · Physics 2009-11-11 B. W. Holwerda , R. A. González , Ronald J. Allen , P. C. van der Kruit

We demonstrate that the observed increase of some nebular line ratios with height above the midplane in the diffuse ionized gas (DIG) in the Milky Way and other galaxies is a natural consequence of the progressive hardening of the radiation…

Astrophysics · Physics 2009-11-10 Kenneth Wood , John S. Mathis

Observations show that magnetic fields in the interstellar medium (ISM) often do not respond to increases in gas density as would be naively expected for a frozen-in field. This may suggest that the magnetic field in the diffuse gas becomes…

Astrophysics of Galaxies · Physics 2009-11-13 A. Fletcher , M. Korpi , A. Shukurov

We report on probability-density-functions (PDF) of the mass density in numerical simulations of highly compressible hydrodynamic flows and the corresponding structure formation of Lagrangian particles advected by the flows. Numerical…

Fluid Dynamics · Physics 2009-11-13 Christoph Beetz , Christian Schwarz , Jürgen Dreher , Rainer Grauer

In most studies of dust in galaxies, dust is only detected from its emission to approximately the optical radius of the galaxy. By combining the signal of 110 spiral galaxies observed as part of the Herschel Reference Survey, we are able to…

The mass fraction of dense gas within giant molecular clouds (GMCs) of the Milky Way is investigated using 13CO data from the FCRAO Galactic Plane Surveys and the Bolocam Galactic Plane Survey (BGPS) of 1.1 mm dust continuum emission. A…

Astrophysics of Galaxies · Physics 2015-06-18 Andrew J. Battisti , Mark H. Heyer

An accurate estimate of the interstellar gas density distribution is crucial to understanding the interstellar medium (ISM) and Galactic cosmic rays (CRs). To comprehend the ISM and CRs in a local environment, a study of the diffuse…

High Energy Astrophysical Phenomena · Physics 2020-02-26 T. Mizuno , S. Abdollahi , Y. Fukui , K. Hayashi , T. Koyama , A. Okumura , H. Tajima , H. Yamamoto

We analyze the radial distribution of HI gas for 23 disk galaxies with unusually high HI content from the Bluedisk sample, along with a similar-sized sample of "normal" galaxies. We propose an empirical model to fit the radial profile of…

I review studies of the hot gaseous medium in and around nearby normal disk galaxies, including the Milky Way. This medium represents a reservoir of materials required for lasting star formation, a depository of galactic feedback (e.g.,…

Astrophysics · Physics 2009-11-11 Q. Daniel Wang

Ionization feedback should impact the probability distribution function (PDF) of the column density around the ionized gas. We aim to quantify this effect and discuss its potential link to the Core and Initial Mass Function (CMF/IMF). We…

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