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https://stockholmuniversity.zoom.us/j/940229961
Magnetic buoyancy instability is an extensively studied mechanism which gives insights into dynamics of galaxies. The non-linear phase of this instability is not well understood. We simulate a disk galaxy with the non-linear magneto-hydrodynamic equations on a three-dimensional Cartesian grid using the Pencil Code. We study the evolution and saturation of the magnetic buoyancy instability or Parker instability. The vertically stratified system is initialized in magneto-hydrostatic equilibrium under a chosen gravitational field profile. The evolution and saturation of the instabilities studied for two different gravitational fields. First, we implement the gravitational profile used in Giz & Shu (1993) [1] and we also study the instability in the gravitational field from Kuijken & Gilmore (1989) [2] to obtain a more realistic picture of the galaxy. The perturbations to the imposed initial fields are evolved according to the non-linear equations. At early times, we observe a linear growth phase, which is in agreement with previous analytical and numerical works. We also compare the simulations with a dispersion relation from an analytical model. At later times, the system enters a non-linear saturated state. In this regime, we obtain systematic outflow in the system.
References:
[1] Giz, A. T., & Shu, F. H. 1993, ApJ, 404, 185
[2] Kuijken K., Gilmore G., 1989, MNRAS, 239, 571