Back to Volume
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.
Back to Volume