Blue Waters Symposium 2019

Galaxy formation is quite numerically challenging, due to the wide range of physics and physical scales involved.  In this talk I present two results from our collaboration’s simulation campaign to explore galaxy collaboration over the entire age of the universe on Blue Waters, which has spanned three PRAC grants, one GLCPC allocation, and the entirety of the Blue Waters lifecycle.  The first result is the discovery of a new mechanism for the formation of supermassive black holes in the early universe (Wise et al. 2019, Nature), which unlike much previous work provides a natural explanation for the abundance of incredible massive black holes observed in the universe roughly a billion years after the Big Bang.  The second result explores the diffuse circumgalactic plasma around Milky Way galaxies using incredibly high spatial resolution, and shows that this increased (and expensive!) resolution is crucial to resolving hydrothermal instabilities in this gas, thus understanding observations of present-day galaxies.  These results are exemplars of the type of theoretical studies that are only possible on capability-scale supercomputers, and I close the talk by highlighting two codes, Enzo-E and K-Athena, that build on lessons learned with Blue Waters in order to be both scalable and highly performant on future exascale supercomputers.