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Although there are a wealth of column density tracers for both the molecular and diffuse interstellar medium, there are very few observational studies investigating the relationship between the density variance ($\sigma^2$) and the sonic…

Astrophysics of Galaxies · Physics 2015-06-05 Blakesley Burkhart , A. Lazarian

We examine the relation between the density variance and the mean-square Mach number in supersonic, isothermal turbulence, assumed in several recent analytic models of the star formation process. From a series of calculations of supersonic,…

Astrophysics of Galaxies · Physics 2015-05-20 Daniel J. Price , Christoph Federrath , Christopher M. Brunt

The probability density function (PDF) of the gas density in subsonic and supersonic, isothermal, driven turbulence is analyzed with a systematic set of hydrodynamical grid simulations with resolutions up to 1024^3 cells. We performed a…

Solar and Stellar Astrophysics · Physics 2014-11-27 Lukas Konstandin , Philipp Girichidis , Christoph Federrath , Ralf S. Klessen

(Abridged) Many of the observed CO line profiles exhibit broad linewidths that greatly exceed the thermal broadening expected within molecular clouds. These suprathermal CO linewidths are assumed to be originated from the presence of…

Astrophysics of Galaxies · Physics 2016-06-22 A. Hacar , J. Alves , A. Burkert , P. Goldsmith

Supersonic turbulence in molecular clouds is a key agent in generating density enhancements that may subsequently go on to form stars. The stronger the turbulence - the higher the Mach number - the more extreme the density fluctuations are…

Astrophysics of Galaxies · Physics 2015-05-18 Chris Brunt

Understanding the role of turbulence in shaping the interstellar medium (ISM) is crucial for studying star formation, molecular cloud evolution, and cosmic ray propagation. Central to this is the measurement of the sonic Mach number…

Astrophysics of Galaxies · Physics 2025-02-06 Tyler Schmaltz , Yue Hu , Alex Lazarian

We study the anisotropy of centroid and integrated intensity maps with synthetic observations. We perform post-process radiative transfer including the optically thick regime that was not covered in Hern\'andez-Padilla et al. (2020). We…

Astrophysics of Galaxies · Physics 2024-06-25 D. Hernández-Padilla , A. Esquivel , A. Lazarian , P. F. Velázquez , J. Cho

It is widely accepted that supersonic, magnetised turbulence plays a fundamental role for star formation in molecular clouds. It produces the initial dense gas seeds out of which new stars can form. However, the exact relation between gas…

Astrophysics of Galaxies · Physics 2012-04-13 F. Z. Molina , S. C. O. Glover , C. Federrath , R. S. Klessen

The Fourier power spectrum is one of the most widely used statistical tools to analyze the nature of magnetohydrodynamic turbulence in the interstellar medium. Lazarian & Pogosyan (2004) predicted that the spectral slope should saturate to…

Astrophysics of Galaxies · Physics 2015-06-15 Blakesley Burkhart , A. Lazarian , V. Ossenkopf , J. Stutzki

We model driven, compressible, isothermal, turbulence with Mach numbers ranging from the subsonic ($\mathcal{M} \approx 0.65$) to the highly supersonic regime ($\mathcal{M}\approx 16 $). The forcing scheme consists both solenoidal…

Solar and Stellar Astrophysics · Physics 2016-06-15 Lukas Konstandin , Wolfram Schmidt , Philipp Girichidis , Thomas Peters , Rahul Shetty , Ralf S. Klessen

In an effort to characterize the Mach numbers of ISM magnetohydrodynamic (MHD) turbulence, we study the probability distribution functions (PDFs) of patial increments of density, velocity, and magnetic field for fourteen ideal isothermal…

Astrophysics of Galaxies · Physics 2015-05-27 Benjamin M. Tofflemire , Blakesley Burkhart , A. Lazarian

Molecular line observations using a variety of tracers are often used to investigate the kinematic structure of molecular clouds. However, measurements of cloud velocity dispersions with different lines, even in the same region, often yield…

Astrophysics of Galaxies · Physics 2020-09-30 Yuxuan Yuan , Mark R. Krumholz , Blakesley Burkhart

[abridged] We determine the relationship between turbulence energy and gas density variance for 15 molecular clouds in the Solar neighbourhood. We use the linewidths of the CO molecule as the probe of the turbulence energy (sonic Mach…

Astrophysics of Galaxies · Physics 2017-12-06 Jouni Kainulainen , Christoph Federrath

Turbulence influences the structure and dynamics of molecular clouds, and plays a key role in regulating star formation. We therefore need methods to accurately infer turbulence properties of molecular clouds from position-position-velocity…

Astrophysics of Galaxies · Physics 2025-09-12 Jayashree Narayan , Aris Tritsis , Christoph Federrath

Supersonic turbulence is a key player in controlling the structure and star formation potential of molecular clouds (MCs). The three-dimensional (3D) turbulent Mach number, $\mathcal{M}$, allows us to predict the rate of star formation.…

Astrophysics of Galaxies · Physics 2019-07-17 James R. Beattie , Christoph Federrath , Ralf S. Klessen , Nicola Schneider

We compare the structure of synthetic dust polarization with synthetic molecular line emission from radiative transfer calculations using a 3-dimensional, turbulent collapsing-cloud magnetohydrodynamics simulation. The histogram of relative…

Astrophysics of Galaxies · Physics 2023-03-29 Renato Mazzei , Zhi-Yun Li , Che-Yu Chen , Laura Fissel , Mike Chen , James Park

We present a comparison of molecular clouds (MCs) from a simulation of supernova-driven interstellar medium (ISM) turbulence with real MCs from the Outer Galaxy Survey. The radiative transfer calculations to compute synthetic CO spectra are…

Astrophysics of Galaxies · Physics 2016-08-03 Paolo Padoan , Mika Juvela , Liubin Pan , Troels Haugbølle , Åke Nordlund

We perform three-dimensional (3D) compressible MHD simulations over many dynamical times for an extended range of sonic and Alfven Mach numbers and analyze the statistics of 3D density and 2D column density, which include probability…

Astrophysics · Physics 2009-01-19 G. Kowal , A. Lazarian , A. Beresnyak

Understanding the physics of turbulence is crucial for many applications, including weather, industry, and astrophysics. In the interstellar medium (ISM), supersonic turbulence plays a crucial role in controlling the gas density and…

Astrophysics of Galaxies · Physics 2021-01-15 Christoph Federrath , Ralf S. Klessen , Luigi Iapichino , James R. Beattie

Colliding supersonic bulk flows shape observable properties and internal physics of various astrophysical objects, like O-star winds, molecular clouds, galactic sheets, binaries, or gamma-ray bursts. Using numerical simulations, we show…

Solar and Stellar Astrophysics · Physics 2014-01-07 Doris Folini , Rolf Walder , Jean M. Favre
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