New Results from The Cosmic Dawn ("CoDa") Project: Simulating Reionization and Galaxy Formation

I will present the latest results of The Cosmic Dawn ("CoDa") Project, to simulate the Epoch of Reionization, during the first billion years of cosmic time. When the first galaxies formed massive stars whose UV radiation escaped into the cold, neutral intergalactic medium (IGM), giant H II regions were created that grew in size and number until they overlapped. Galaxy formation and reionization were correlated and fully-coupled from the beginning. To model this, we must track galaxy formation and reionization and their mutual feedback, including escape of ionizing starlight from galaxies, which heated and pressurized the IGM, suppressing gravitational infall of baryons and depriving galaxies of fuel for further star formation. The CoDa Project recently achieved a new milestone - CoDa III – with a trillion computational elements -- (8192)^3 particles for dark matter (and additional star particles) and (8192)^3 grid cells for gas and radiation -- the largest rad-hydro simulation to date of fully-coupled reionization and galaxy formation, in a 100 cMpc volume, with enough resolving power to follow the millions of galaxies responsible for its reionization. CoDa III required running hybrid CPU-GPU code RAMSES-CUDATON for 10 days on supercomputer Summit at Oak Ridge Leadership Computing Facility (OLCF), utilizing 131,072 CPU processors and 24,576 GPUs. New results of CoDa III and predecessor CoDa simulations will be presented and predictions compared with the latest observations (e.g. HST, JWST).