Understanding the role galactic-scale winds play in the formation and evolution of galaxies is a fundamental goal of current astrophysical research. Galactic winds, driven by energetic feedback processes associated with supernovae, regulate the baryonic content, star formation rates, and stellar masses of galaxies. To understand the properties of galaxies throughout cosmic time, astrophysical theory must endeavor to model the hydrodynamic processes that govern how gas is ejected from galaxies. The corresponding need for sophisticated simulations of galactic outflows was identified as a prime theoretical challenge in astrophysics for the next decade by the National Research Council. This project aims to meet this challenge by leveraging Titan’s GPU power to simulate galactic outflows with numerical models that allow for supersonic wind velocities, quantify the importance of radiative cooling for the multiphase structure of observed galactic outflows, and determine the mass and energy coupling of ISM gas to supernova-driven outflows.
To perform these simulations, the team will use the Computational Hydrodynamics on parLLel Architectures (Cholla) code (Schneider & Robertson 2015) that performs all its hydrodynamics calculations on GPUs. Cholla has demonstrated excellent weak scaling on up to ~90% of the entire Titan system (16,384 GPUs). Using Titan, Cholla can begin resolving the multiphase structure of galactic outflows and revealing how mass and energy are entrained into a hot wind.
The proposed simulations will greatly extend our physical understanding of galactic outflows by meeting a wide range of scientific goals. They will improve theoretical models for the mass and momentum loading of interstellar gas into baryonic outflows, and better characterize the multiphase structure of supernova-driven galactic winds. In addition, they have the potential to prove the validity of recently developed key analytic theories regarding the large-scale cooling of these winds. Such theories are critical for explaining the observations of large reservoirs of gas in galaxy halos begun to be observed in detail only in the past decade.
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