INTERSTELLAR SONIC AND ALFVENIC MACH NUMBERS AND THE TSALLIS DISTRIBUTION

Journal Article · Wed Jul 20 00:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/736/1/60· OSTI ID:21578303

Tofflemire, Benjamin M ^[1]; Burkhart, Blakesley; Lazarian, A ^[2]

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1. Astronomy Department, University of Washington, Box 351580 Seattle, WA 98195 (United States)
2. Astronomy Department, University of Wisconsin, Madison, 475 N. Charter St., WI 53711 (United States)

In an effort to characterize the Mach numbers of interstellar medium (ISM) magnetohydrodynamic (MHD) turbulence, we study the probability distribution functions (PDFs) of spatial increments of density, velocity, and magnetic field for 14 ideal isothermal MHD simulations at a resolution of 512{sup 3}. In particular, we fit the PDFs using the Tsallis function and study the dependency of the fit parameters on the compressibility and magnetization of the gas. We find that the Tsallis function fits PDFs of MHD turbulence well, with fit parameters showing sensitivities to the sonic and Alfven Mach numbers. For three-dimensional density, column density, and Position-Position-Velocity data, we find that the amplitude and width of the PDFs show a dependency on the sonic Mach number. We also find that the width of the PDF is sensitive to the global Alfvenic Mach number especially in cases where the sonic number is high. These dependencies are also found for mock observational cases, where cloud-like boundary conditions, smoothing, and noise are introduced. The ability of Tsallis statistics to characterize the sonic and Alfvenic Mach numbers of simulated ISM turbulence points to it being a useful tool in the analysis of the observed ISM, especially when used simultaneously with other statistical techniques.

• OSTI ID: 21578303
• Journal Information: Astrophysical Journal, Vol. 736, Issue 1; Other Information: DOI: 10.1088/0004-637X/736/1/60; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
DENSITY
DISTRIBUTION FUNCTIONS
INTERSTELLAR SPACE
MACH NUMBER
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MATTER
SIMULATION
THREE-DIMENSIONAL CALCULATIONS
TURBULENCE
DIMENSIONLESS NUMBERS
FLUID MECHANICS
FUNCTIONS
HYDRODYNAMICS
MECHANICS
PHYSICAL PROPERTIES
SPACE
VELOCITY