VERTICAL STRUCTURE OF A SUPERNOVA-DRIVEN TURBULENT, MAGNETIZED INTERSTELLAR MEDIUM
- Department of Astronomy, University of Wisconsin-Madison, Madison, WI (United States)
- Department of Astronomy, Columbia University, New York, NY (United States)
- Department of Astrophysics, American Museum of Natural History, New York, NY (United States)
- Department of Physics, University of Wisconsin-Whitewater, Whitewater, WI (United States)
- Department of Mathematics, Wuerzburg University, Emil Fischer Strasse 30, Wuerzburg (Germany)
- Department of Applied Mathematics, University of Washington, Seattle, WA (United States)
Stellar feedback drives the circulation of matter from the disk to the halo of galaxies. We perform three-dimensional magnetohydrodynamic simulations of a vertical column of the interstellar medium with initial conditions typical of the solar circle in which supernovae drive turbulence and determine the vertical stratification of the medium. The simulations were run using a stable, positivity-preserving scheme for ideal MHD implemented in the FLASH code. We find that the majority ( Almost-Equal-To 90%) of the mass is contained in thermally stable temperature regimes of cold molecular and atomic gas at T < 200 K or warm atomic and ionized gas at 5000 K < T < 10{sup 4.2} K, with strong peaks in probability distribution functions of temperature in both the cold and warm regimes. The 200-10{sup 4.2} K gas fills 50%-60% of the volume near the plane, with hotter gas associated with supernova remnants (30%-40%) and cold clouds (<10%) embedded within. At |z| {approx} 1-2 kpc, transition-temperature (10{sup 5} K) gas accounts for most of the mass and volume, while hot gas dominates at |z| > 3 kpc. The magnetic field in our models has no significant impact on the scale heights of gas in each temperature regime; the magnetic tension force is approximately equal to and opposite the magnetic pressure, so the addition of the field does not significantly affect the vertical support of the gas. The addition of a magnetic field does reduce the fraction of gas in the cold (<200 K) regime with a corresponding increase in the fraction of warm ({approx}10{sup 4} K) gas. However, our models lack rotational shear and thus have no large-scale dynamo, which reduces the role of the field in the models compared to reality. The supernovae drive oscillations in the vertical distribution of halo gas, with the period of the oscillations ranging from Almost-Equal-To 30 Myr in the T < 200 K gas to {approx}100 Myr in the 10{sup 6} K gas, in line with predictions by Walters and Cox.
- OSTI ID:
- 22034521
- Journal Information:
- Astrophysical Journal, Vol. 750, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ASTRONOMY
ASTROPHYSICS
COMPUTERIZED SIMULATION
DISTRIBUTION FUNCTIONS
GALAXIES
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MASS
OSCILLATIONS
PROBABILITY
SHEAR
STRATIFICATION
SUPERNOVA REMNANTS
SUPERNOVAE
THREE-DIMENSIONAL CALCULATIONS
TRANSITION TEMPERATURE
TURBULENCE