Due to the finite speed of light, astronomers can literally look back in time by observing objects at very large distances. This allows them to test theories about the evolution of the universe essentially from the time of the Big Bang, nearly 13.7 billion years ago, to the present. One of the outstanding open questions in these theories is how the first galaxies formed out of the nearly uniform neutral gas of hydrogen and helium left over from the Big Bang. This project aims to use sophisticated computer models to take the initial conditions imprinted on the universe by the Big Bang and follow their evolution as the first generation of stars are formed in newly-formed galaxies. Supernova explosions of these stars will, in turn, drive winds from the galaxies that will enrich the material between galaxies with heavier elements produced in the supernovas. The project will provide estimates of observational signatures of the early galaxies and the imprint of the heavy elements on the light from distant quasars. Although this epoch of the universe's evolution cannot be studied with current telescopes because the stars and galaxies are so dim, new instruments such as the James Webb Space Telescope will be able to observe these extremely faint objects so the work done here will help guide the crafting of observational programs thereby optimally utilizing the new instruments when they are available.
The goal of this project is to investigate a significant and open question in modern astrophysics: the assembly of the first galaxies. The epoch of galaxy formation is one of the remaining gaps in our understanding of the evolution of the universe and the development of structure from the imprint of the Big Bang on the early universe. Specifically, the project will study the role of galactic winds driven by supernovae, i.e., starburst-driven stellar feedback, on the enabling of re-ionization. Hydrodynamic simulations will elucidate the physics of the starburst-energized interstellar medium and the mechanics of newly-created metals. Synthetic spectra from the models will be used to identify the signatures of high-redshift starbursts in dwarf galaxies. Furthermore, models will improve our understanding of metal enrichment of the high-redshift intergalactic medium witnessed by absorption lines in the spectra of high-redshift quasars. This work will be a first-step precursor for the interpretation of observations taken with JWST and will the next generation of large ground-based telescopes as well as in-situ measurements of extremely metal-poor stars in the Milky Way and other Local Group galaxies. In addition, graduate students will be trained for careers in theoretical physics and also in cutting-edge techniques of numerical simulation and visualization. These skills are also vital in other disciplines that rely on multi-scale modeling and large-scale scientific computing, spanning areas from medical imaging and subsurface imaging to engineering and validation of high-energy-density processes. In addition, the project team will organize a five-day summer school for approximately 60 graduate students on "Numerical Astrophysics at the High-Redshift Frontier."
