NSF-BSF: The Origin of the Excess of Bright Galaxies at Cosmic Dawn

There are an unexpectedly large number of bright galaxies with extremely high luminosities, which suggests star formation rates 100 times more than our own Milky Way today. The investigators will look at high-redshift massive dark matter halos to assess whether the physical conditions in these systems could explain the existing observations. They will test the hypothesis that these galaxies host a new type of interstellar medium, in which stellar feedback cannot regulate star formation. Understanding star formation and feedback in such an extreme environment will test several competing theories regarding the physics of the interstellar medium and its effect on galaxy formation. The project will also support two-week summer internships for local high-school students. The researchers will study the evolution of massive halos at Cosmic Dawn. The simulation effort will be based on the Adaptive Mesh Refinement cosmological fluid code RAMSES applied to 10 massive halos extracted from simulated catalogs. The simulations will incorporate subgrid turbulence, a turbulent dynamo model promoting strong magnetic fields and cosmic ray feedback, fully coupled radiative transfer in different photon groups with various thermal and dynamical effects on the gas. The analytic modeling will be used to guide and interpret the simulations. It will also provide a framework for developing a new semi-analytival model suitable for these high-redshift galaxies. The project will produce JWST mock observations from the models. JWST observations will continue to arrive at a steadily increasing pace and this project will leverage the best available data on the high-redshift Universe. The local high school internships will focus on computer simulations and visualizations in astronomy. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.