Anywhere that there is a fluid in motion, whether liquid or gas, there will be turbulence. These disturbances to the flow can be very significant, but their possibly profound effect on the formation of galaxies out of the cosmic gas remains an area of mystery in our fundamental understanding of how the Universe evolves. This work seeks to correct this lack, using high powered computers to carry out novel numerical simulations with very high resolution. For the first time, pretty well all of the physics involved in forming stars within galaxies will be included. The calculations will be intimately connected with telescope data, both checking the computer results and helping to understand the observations. The new ideas will also be useful for other studies of turbulent fluids.
Cosmic gas flows have high velocities, span enormous scales, and are highly turbulent, but the possibly profound effects of turbulence on galaxy formation are largely unexplored. This project is a systematic exploration of turbulence and its effects on accretion flows, star formation, and the structure of galaxies, in self-consistent cosmological simulations using adaptive mesh refinement (AMR). Part of the work will implement and test a novel model for sub-grid scale turbulence and use it to estimate local turbulent stresses. This model will be used to add new physically-motivated prescriptions for star formation into the galaxy formation simulations, incorporating a rich set of physical processes thought to be critical for comparison with observations, including modeling of molecular hydrogen, chemical enrichment and evolution, dust formation and destruction, radiative transfer of ionizing and far-ultraviolet radiation, star formation, and stellar feedback with radiation pressure and cosmic rays. Observational comparisons will test and inform the theoretical models, while the simulation results will help to understand the data. Scientific results will include quantifying the effects of turbulence on the cold accretion gas flows onto galaxies, assessing the relative contribution of dynamical drivers of turbulence, and quantifying the effects of turbulence on the density structure of the gas. The emphasis on observational comparisons will make this study particularly valuable for interpreting the results from current and future facilities. Both the methods and the results will be of value for other simulations and for semi-analytic models. The simulations also lend themselves well to high-fidelity, scientifically-accurate visualizations well suited to the high resolution environment of full-dome planetarium projectors, but of value to all planetaria.
