Simulating Faintest Galaxies in the JWST Era

Nickolay Gnedin, University of Chicago

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The study of cosmic reionization—the process of ionization of the bulk of cosmic gas by high energy radiation from early galaxies—is one of the most promising areas of astrophysical research in the current decade. The end of this decade will see an amazing increase in observational capabilities for the epoch of reionization. The breakthrough is spearheaded by the James Webb Space Telescope (JWST), the flagship NASA mission for this and next decade, as well as several other observational developments to follow. All there observational probes will flood the field with high quality observational data, whose reach will be limited unless the observational progress can be met with equivalent advances in theory, of which numerical modeling is a primary tool.

One of the JWST primary science goals is to push the detection limit of high redshift galaxies to sufficiently faint levels, where the luminosity function is expected to "turn over." The primary scientific goal of this project is to use the petascale capabilities of Blue Waters to explore the physical mechanisms for the turnover at the faint end of the galaxy UV luminosity function. Since the JWST reach is sufficient to detect the expected turnover in cluster-lensed "Frontier Fields," theory must be ready to confront such observations with adequate interpretive tools. This project is part of the Cosmic Reionization On Computers project. The ultimate goal of the project is to develop simulation technology to be able to model fully all relevant physics, from radiative transfer to gas dynamics and star formation, in simulation volumes of over 100 comoving Mpc and with spatial resolution approaching 100 pc in physical units, thus covering the full range of spatial, temporal, and mass scales relevant to modeling reionization.

In terms of broader impacts, this project will serve as a vehicle for professional training of graduate students in high performance computing. In addition, this project has substantial outreach potential via a strong connection between the University of Chicago and Adler Planetarium.