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Column-density maps of molecular clouds are one of the most important observables in the context of molecular cloud- and star-formation (SF) studies. With the Herschel satellite it is now possible to determine the column density from dust…

Astrophysics of Galaxies · Physics 2015-03-04 N. Schneider , V. Ossenkopf , T. Csengeri , R. Klessen , C. Federrath , P. Tremblin , P. Girichidis , S. Bontemps , Ph. Andre

We quantitatively study the probability distribution function (PDF) of cosmological nonlinear density fluctuations from N-body simulations with Gaussian initial condition. In particular, we examine the validity and limitations of one-point…

Astrophysics · Physics 2009-11-06 Issha Kayo , Atsushi Taruya , Yasushi Suto

We use a suite of 3D simulations of star-forming molecular clouds, with and without stellar feedback and magnetic fields, to investigate the effectiveness of different fitting methods for volume and column density probability distribution…

Astrophysics of Galaxies · Physics 2023-05-22 Avery Kiihne , Sabrina M. Appel , Blakesley Burkhart , Vadim A. Semenov , Christoph Federrath

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

Column density (N) PDFs serve as a powerful tool to characterize the physical processes that influence the structure of molecular clouds. Star-forming clouds can best be characterized by lognormal PDFs for the lower N range and a power-law…

The density distribution within molecular clouds offers critical insights into their underlying physical processes, which are essential for understanding star formation. As a statistical measure of column density on the cloud scale, the…

Astrophysics of Galaxies · Physics 2026-01-12 Yuchen Xing , Keping Qiu

We numerically study the volume density probability distribution function (n-PDF) and the column density probability distribution function (Sigma-PDF) resulting from thermally bistable turbulent flows. We analyze three-dimensional…

Astrophysics of Galaxies · Physics 2015-06-12 Adriana Gazol , Jongsoo Kim

The probability distribution functions (PDFs) of the average densities of the diffuse ionized gas (DIG) and the diffuse atomic gas are close to lognormal, especially when lines of sight at |b|<5 degree and |b|>5 degree are considered…

Astrophysics of Galaxies · Physics 2015-05-27 Elly M. Berkhuijsen , Andrew Fletcher

Power-law tails are often seen in probability density functions (PDFs) of molecular cloud column densities, and have been attributed to the effect of gravity. We show that extinction PDFs of a sample of five molecular clouds obtained at a…

Astrophysics of Galaxies · Physics 2015-06-24 Chris Brunt

The probability distribution functions (PDFs) for atomic, molecular, and total gas surface densities of M33 are determined at a resolution of about 50~pc over regions that share coherent morphological properties to unveil fingerprints of…

Astrophysics of Galaxies · Physics 2018-10-03 Edvige Corbelli , Bruce G. Elmegreen , Jonathan Braine , David Thilker

The one-point statistics of column density distributions of turbulent molecular cloud models are investigated and compared with observations. In agreement with the observations, the number N of pixels with surface density S is distributed…

Astrophysics · Physics 2007-05-23 Andreas Burkert , Mordecai-Mark Mac Low

We present N-PDFs of 29 Galactic regions obtained from Herschel imaging at high angular resolution, covering diffuse and quiescent clouds, and those showing low-, intermediate-, and high-mass star formation (SF), and characterize the cloud…

We investigate the form of the one-point probability distribution function (pdf) for the density field of the interstellar medium using numerical simulations that successively reduce the number of physical processes included.…

Astrophysics · Physics 2014-10-13 J. Scalo , E. Vazquez-Semadeni , D. Chappell , T. Passot

The probability density function (PDF) of flux $R$ is computed in systems with logarithmic non-linearity using a model non-linear dynamical equation. The PDF tails of the first moment flux are analytically predicted to be power law. These…

Plasma Physics · Physics 2010-03-12 Johan Anderson , Eun-jin Kim

We investigate the behavior of the magnetic pressure, $b^2$, in fully turbulent MHD flows in ``1+2/3'' dimensions by means of its effect on the probability density function (PDF) of the density field. We start by reviewing our previous…

Astrophysics · Physics 2007-05-23 Enrique Vazquez-Semadeni , Thierry Passot

We study the probability distribution function (PDF) of the mass density in simulations of supersonic turbulence with properties appropriate for molecular clouds. For this study we use Athena, a new higher-order Godunov code. We find there…

Astrophysics · Physics 2008-09-23 M. Nicole Lemaster , James M. Stone

We focus on the probability distribution function (pdf) $P(\Delta \gamma; \gamma)$ where $\Delta \gamma$ are the {\em measured} strain intervals between plastic events in an athermal strained amorphous solids, and $\gamma$ measures the…

Soft Condensed Matter · Physics 2016-01-20 H. G. E. Hentschel , Prabhat K. Jaiswal , Itamar Procaccia , Srikanth Sastry

We present a far-IR survey of the entire Mon R2 GMC with $Herschel-SPIRE$ cross-calibrated with $Planck-HFI$ data. We fit the SEDs of each pixel with a greybody function and an optimal beta value of 1.8. We find that mid-range column…

Astrophysics of Galaxies · Physics 2016-06-07 R. Pokhrel , R. Gutermuth , B. Ali , T. Megeath , J. Pipher , P. Myers , W. J. Fischer , T. Henning , S. J. Wolk , L. Allen , J. J. Tobin

A key parameter to the description of all star formation processes is the density structure of the gas. In this letter, we make use of probability distribution functions (PDFs) of Herschel column density maps of Orion B, Aquila, and…

We analyse column density and temperature maps derived from Herschel dust continuum observations of a sample of massive infrared dark clouds (G11.11-0.12, G18.82-0.28, G28.37+0.07, G28.53-0.25). We disentangle the velocity structure of the…

Astrophysics of Galaxies · Physics 2015-05-27 N. Schneider , T. Csengeri , R. S. Klessen , P. Tremblin , V. Ossenkopf , N. Peretto , R. Simon , S. Bontemps , C. Federrath