VELOCITY ANISOTROPY AS A DIAGNOSTIC OF THE MAGNETIZATION OF THE INTERSTELLAR MEDIUM AND MOLECULAR CLOUDS

Journal Article · Thu Oct 20 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/740/2/117; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21587346

Esquivel, A ^[1]; Lazarian, A ^[2]

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1. Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, 04510 Mexico D.F. (Mexico)
2. Astronomy Department, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706-1582 (United States)

We use a set of magnetohydrodynamic simulations of fully developed (driven) turbulence to study the anisotropy in the velocity field that is induced by the presence of the magnetic field. In our models, we study turbulence characterized by sonic Mach numbers M{sub s} from 0.7 to 7.5 and Alfven Mach numbers from 0.4 to 7.7. These are used to produce synthetic observations (centroid maps) that are then analyzed. To study the effect of large-scale density fluctuations and of white noise, we have modified the density fields and obtained new centroid maps, which are analyzed. We show that restricting the range of scales at which the anisotropy is measured makes the method robust against such fluctuations. We show that the anisotropy in the structure function of the maps reveals the direction of the magnetic field for M{sub A} {approx}< 1.5, regardless of the sonic Mach number. We find that the degree of anisotropy can be used to determine the degree of magnetization (i.e., M{sub A} ) for M{sub A} {approx}< 1.5. To do this, one needs an additional measure of the sonic Mach number and an estimate of the line of sight magnetic field, both feasible by other techniques, offering a new opportunity to study the magnetization state of the interstellar medium.

• OSTI ID: 21587346
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 740; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANISOTROPY
CLOUDS
DENSITY
DIMENSIONLESS NUMBERS
FLUCTUATIONS
FLUID MECHANICS
FUNCTIONS
HYDRODYNAMICS
MACH NUMBER
MAGNETIC FIELDS
MAGNETIZATION
MAGNETOHYDRODYNAMICS
MECHANICS
PHYSICAL PROPERTIES
SIMULATION
STRUCTURE FUNCTIONS
TURBULENCE
VARIATIONS
VELOCITY