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| Paper: |
Simulating Supersonic Turbulence in Galaxy Formation |
| Volume: |
453, Advances in Computational Astrophysics: Methods, Tools, and Outcome |
| Page: |
273 |
| Authors: |
Scannapieco, E.; Brüggen, M.; Pan, L. |
| Abstract: |
We present a series of simulations that study the role of supersonic turbulence in galaxy formation.
First, we describe a detailed numerical study to compare the mixing rate of metals
to the thermalization rate of kinetic energy in a supersonic turbulent medium.
Our simulations show that the scalar mixing timescale increases modestly with Mach number,
as compressible modes are less efficient in enhancing mixing than solenoidal modes. However,
since most of kinetic energy is always contained in solenoidal
modes, the ratio of mixing and thermalization timescales varies by only
a factor of ≈ 2 over a wide range of Mach numbers.
Building on these results, we present adaptive mesh simulations of
galaxy outflows that use a subgrid model to track turbulent velocities and
length scales. Unlike previous approaches, this method allows us to deposit energy from supernovae
directly into supersonic turbulence, and we are able to simulate a
starbursting galaxy, with realistic radiative
cooling throughout the simulation. Pockets of hot, diffuse gas
around individual stellar associations sweep up shells of material
that persist for long times due to the cooling instability, and this
leads to a complex, distribution of bubbles, loops
and filaments as observed in outflowing galaxies. The
overlapping of hot, rarefied regions leads to a collective
central outflow that escapes the galaxy by eating away at the
exterior gas through turbulent mixing. |
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