New 'Lumina' Simulation Maps First Two Billion Years of Cosmic Evolution

A team led by researchers at the Harvard-Smithsonian Center for Astrophysics has produced Lumina, the most extensive radiation-hydrodynamics simulation of the early universe to date. Spanning a volume of 1.5 billion light-years on each side, the model is 100 times larger than any prior effort and resolves individual galaxies, stars and black holes while following the evolution of hydrogen and helium. For the first time, scientists can observe helium reionisation as ultraviolet radiation from nascent stars creates expanding ionised bubbles.

The project required more than 15,000 GPUs running on the Frontier supercomputer at Oak Ridge National Laboratory in Tennessee. Visualisations from Lumina reveal the intricate filaments of dark matter and fast-moving gas that shaped the cosmic web. Researchers say the simulation will serve as a benchmark for interpreting observations from the James Webb and Nancy Grace Roman Space Telescopes, testing whether current cosmological theories hold up.