Harvard-Smithsonian Team Releases Large-Scale Early Universe Simulation

Astronomers at the Center for Astrophysics | Harvard & Smithsonian have introduced "Lumina," one of the most extensive radiation-hydrodynamics simulations of the early universe. The model reproduces interactions among ordinary matter, dark matter and radiation during the first two billion years after the Big Bang, providing a benchmark for comparing data from the James Webb Space Telescope, the Nancy Roman Space Telescope and other observatories.

The simulation spans a cubic region about 1.5 billion light-years on a side—over 100 times larger than previous comparable runs—and is the first to incorporate helium reionization with immediate feedback on the evolving cosmos. It tracks the emergence of the earliest galaxies and the transformation of intergalactic gas, offering a platform for testing hypotheses about galaxy formation, gas flows, and the impact of primordial radiation.

"With JWST, the early universe has become an exciting new frontier in astrophysics," said lead author Oliver Zier, an ITC Fellow at the Center for Astrophysics. "To understand what we are seeing with this telescope, we need to translate our theories into detailed predictions."

Aaron Smith, an assistant professor of physics at the University of Texas at Dallas and co-author, added that the simulation allows researchers to follow the evolution of hydrogen and helium across a vast volume while still resolving individual galaxies and luminous objects.

Lumina was generated using more than 15,000 graphics processing units on the Frontier supercomputer at Oak Ridge National Laboratory. The team plans to use the model to explore gas dynamics between galaxies, the role of early radiation in shaping cosmic evolution, and the development of intense star-forming regions.