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We used magnetohydrodynamic (MHD) simulations of interstellar turbulence to study the probability distribution functions (PDFs) of increments of density, velocity, and magnetic field. We found that the PDFs are well described by a Tsallis…

Astrophysics of Galaxies · Physics 2011-08-04 A. Esquivel , A. Lazarian

We present a method to derive the density scaling relation $\langle n\rangle \propto L^{-\alpha}$ in regions of star formation or in their turbulent vicinities from straightforward binning of the column-density distribution ($N$-pdf). The…

Astrophysics of Galaxies · Physics 2017-05-19 Todor Veltchev , Sava Donkov , Orlin Stanchev

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

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

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

Supersonic flows in the interstellar medium (ISM) are believed to be a key driver of the molecular cloud formation and evolution. Among molecular clouds' properties, the ratio between the solenoidal and compressive modes of turbulence plays…

Astrophysics of Galaxies · Physics 2022-05-18 Masato I. N. Kobayashi , Tsuyoshi Inoue , Kengo Tomida , Kazunari Iwasaki , Hiroki Nakatsugawa

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

We aim to better understand how the spatial structure of molecular clouds is governed by turbulence. For that, we study the large-scale spatial distribution of low density molecular gas and search for characteristic length scales. We employ…

Astrophysics of Galaxies · Physics 2015-05-18 N. Schneider , S. Bontemps , R. Simon , V. Ossenkopf , C. Federrath , R. Klessen , F. Motte , P. Andre , J. Stutzki , C. Brunt

(Abridged) We derive an analytical formula which provides estimates on multiscale gravitational energy distribution using the observed surface density PDF. Our analytical formalism also enables one to convert the observed column density PDF…

Solar and Stellar Astrophysics · Physics 2016-07-07 Guang-Xing Li , Andreas Burkert

In recent decades, significant attention has been dedicated to analytical and observational studies of the atomic hydrogen (HI) to molecular hydrogen (H2) transition in the interstellar medium. We focussed on the Draco diffuse cloud to gain…

The one-point probability distribution function (PDF) of the matter density field in the universe is a fundamental property that plays an essential role in cosmology for estimates such as gravitational weak lensing, non-linear clustering,…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-10 Anatoly Klypin , Francisco Prada , Juan Betancort-Rijo , Franco D. Albareti

The probability density functions (PDFs) for energy dissipation rates, created from time-series data of grid turbulence in a wind tunnel, are analyzed in a high precision by the theoretical formulae for PDFs within multifractal PDF theory…

Fluid Dynamics · Physics 2015-06-03 Toshihico Arimitsu , Naoko Arimitsu , Hideaki Mouri

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

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

The structure of molecular clouds (MCs) holds important clues on the physical processes that lead to their formation and subsequent evolution. While it is well established that turbulence imprints a self-similar structure to the clouds,…

We present new high resolution and dynamic range dust column density and temperature maps of the California Molecular Cloud derived from a combination of Planck and Herschel dust-emission maps, and 2MASS NIR dust-extinction maps. We used…

Astrophysics of Galaxies · Physics 2017-10-25 Charles J. Lada , John A. Lewis , Marco Lombardi , João Alves

Molecular clouds are supersonically turbulent. This turbulence governs the initial mass function and the star formation rate. In order to understand the details of star formation, it is therefore essential to understand the properties of…

Astrophysics of Galaxies · Physics 2015-06-17 Adam Ginsburg , Christoph Federrath , Jeremy Darling

The evolution of molecular interstellar clouds is a complex, multi-scale process. The power-law density exponent describes the steepness of density profiles, and it has been used to characterize the density structures of the clouds yet its…

Astrophysics of Galaxies · Physics 2022-05-09 Guang-Xing Li , Ji-Xuan Zhou

We study the effect of density fluctuations induced by turbulence on the HI/H$_2$ structure in photodissociation regions (PDRs) both analytically and numerically. We perform magnetohydrodynamic numerical simulations for both subsonic and…

Astrophysics of Galaxies · Physics 2017-07-26 Shmuel Bialy , Blakesley Burkhart , Amiel Sternberg