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ISM properties in hydrodynamic galaxy simulations: Turbulence cascades, cloud formation, role of gravity and Feedback
Ivanio Puerari
Acceso Abierto
Galaxies: evolution
Galaxies: ISM
Galaxies: star formation
Galaxies: structure
ISM: kinematics and dynamics
ISM: structure
We study the properties of ISM substructure and turbulence in hydrodynamic (AMR) galaxy simulations with resolutions up to 0.8 pc and 5 × 10³ M⊙. We analyse the power spectrum of the density distribution, and various components of the velocity field. We show that the disk thickness is about the average Jeans scale length, and is mainly regulated by gravitational instabilities. From this scale of energy injection, a turbulence cascade towards small-scale is observed, with almost isotropic small-scale motions. On scales larger than the disk thickness, density waves are observed, but there is also a full range of substructures with chaotic and strongly non-isotropic gas velocity dispersions. The power spectrum of vorticity in an LMC-sized model suggests that an inverse cascade of turbulence might be present, altho ugh energy input over a wide range of scales in the coupled gaseous+stellar fluid could also explain this quasi-2D regime on scales larger than the disk scale height. Similar regimes of gas turbulence are also found in massive high-redshift disks with high gas fractions. Disk properties and ISMturbulence appear to be mainly regulated by gravitational processes, both on large scales and inside dense clouds. Star formation feedback is however essential to maintain the ISM in a steady state by balancing a systematic gas dissipation into dense and small clumps. Our galaxy simulations employ a thermal model based on a barotropic Equation of State (EoS) aimed at modelling the equilibrium of gas between various heating and cooling processes. Denser gas is typically colder in this approach, which is shown to correctly reproduce the density structures of a star-forming, turbulent, unstable and cloudy ISM down to scales of a few parsecs.
Monthly Notices of the Royal Astronomical Society
Público en general
Bournaud, F., et al., (2010), ISM properties in hydrodynamic galaxy simulations: Turbulence cascades, cloud formation, role of gravity and Feedback, Monthly Notices of the Royal Astronomical Society, Vol. 409(3): 1088–1099
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Appears in Collections:Artículos de Astrofísica

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