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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…

Stars form from molecular gas under complex conditions influenced by multiple competing physical mechanisms, such as gravity, turbulence, and magnetic fields. However, accurately identifying the fraction of gas actively involved in star…

We investigate the star formation process across the disk of M33 using a multiwavelength dataset and disk dynamics. We computed numerically equilibrium values of gas densities and scale heights across the disk, taking into account dark…

Astrophysics of Galaxies · Physics 2025-08-06 Edvige Corbelli , Bruce Elmegreen , Sara Ellison , Simone Bianchi

One of the targets of the recently launched Fermi Gamma-ray Space Telescope is a diffuse gamma-ray background from dark-matter annihilation or decay in the Galactic halo. N-body simulations and theoretical arguments suggest that the dark…

Astrophysics · Physics 2009-07-22 Samuel K. Lee , Shin'ichiro Ando , Marc Kamionkowski

We present a simple model based on the dark halo approach which provides a useful way to understand key points determining the shape of the non-Gaussian tails of the dark matter one-point probability distribution function(PDF). In…

Astrophysics · Physics 2009-11-07 Atsushi Taruya , Takashi Hamana , Issha Kayo

We propose a new, physically motivated fitting function for density PDFs in turbulent gas. Although it is known that when gas is isothermal, the PDF is approximately lognormal in the core, high-resolution simulations show large deviations…

Astrophysics of Galaxies · Physics 2013-07-02 Philip F. Hopkins

Power spectra of de-projected images of late-type galaxies in gas and/or dust emission are very useful diagnostics of the dynamics and stability of their interstellar medium. Previous studies have shown that the power spectra can be…

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…

It has been recently shown that molecular clouds do not exhibit a unique shape for the column density probability distribution function (Npdf). Instead, clouds without star formation seem to possess a lognormal distribution, while clouds…

The cloud-scale density, velocity dispersion, and gravitational boundedness of the interstellar medium (ISM) vary within and among galaxies. In turbulent models, these properties play key roles in the ability of gas to form stars. New high…

Previously, we showed that surface density profiles of the form of a power-law times a Sersic function satisfy the hydrostatic Jeans equations, a variety of observational constraints, and the condition of a minimal radial entropy profile in…

Astrophysics of Galaxies · Physics 2019-09-27 Curtis Struck , Bruce G. Elmegreen

We use the distance probability density function (DPDF) formalism of Ellsworth-Bowers et al. (2013, 2015) to derive physical properties for the collection of 1,710 Bolocam Galactic Plane Survey (BGPS) version 2 sources with well-constrained…

We measure the velocity dispersion, $\sigma$, and surface density, $\Sigma$, of the molecular gas in nearby galaxies from CO spectral line cubes with spatial resolution $45$-$120$ pc, matched to the size of individual giant molecular…

This paper gives a new way to diagnose the star-forming potential of a molecular cloud region from the probability density function of its column density (N-pdf). It gives expressions for the column density and mass profiles of a symmetric…

Astrophysics of Galaxies · Physics 2015-05-06 Philip C. Myers

Recent observational results indicate that the functional shape of the spatially-resolved star formation-molecular gas density relation depends on the spatial scale considered. These results may indicate a fundamental role of sampling…

Astrophysics of Galaxies · Physics 2015-06-04 Daniela Calzetti , Guilin Liu , Jin Koda

The detailed distribution and kinematics of the atomic and the CO-bright molecular hydrogen in the disc of the Milky Way inside the Solar circle are derived under the assumptions of axisymmetry and pure circular motions. We divide the…

Astrophysics of Galaxies · Physics 2017-11-22 A. Marasco , F. Fraternali , J. M. van der Hulst , T. Oosterloo

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

Aims: We derive the probability density functions (PDFs) of column density for a complete sample of prominent molecular cloud complexes closer than 200 pc. Methods: We derive near-infrared dust extinction maps for 23 molecular cloud…

Astrophysics of Galaxies · Physics 2015-05-14 J. Kainulainen , H. Beuther , T. Henning , R. Plume

It is key to constrain the gas surface density distribution, Sigma_gas, as function of disk radius in protoplanetary disks. In this work we investigate if spatially resolved observations of rarer CO isotopologues may be good tracers of…

Solar and Stellar Astrophysics · Physics 2018-11-14 Anna Miotello , Stefano Facchini , Ewine F. van Dishoeck , Simon Bruderer