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

A team of international researchers has released Lumina, a supercomputer simulation that recreates the universe’s first two billion years, according to a study in Monthly Notices of the Royal Astronomical Society. The model tracks how early stars and black holes drove the reionization era, during which ultraviolet radiation stripped electrons from hydrogen atoms, allowing light to travel farther and influencing galaxy formation.

Lead author Oliver Zier, a postdoctoral research fellow at the Institute for Theory and Computation at the Center for Astrophysics, Harvard & Smithsonian, said the simulation covers a volume more than 100 times larger than previous efforts, spanning roughly 1.5 billion light-years in each direction. "We have a cosmological volume where you can see this cosmic web, how galaxies are clustered. At the same time, we resolve individual galaxies," Zier explained.

The project used over 15,000 graphics processing units on the Frontier supercomputer at Oak Ridge National Laboratory and took nearly three years to complete. Researchers plan to compare Lumina’s output with observations from telescopes such as the James Webb Space Telescope. Zier noted that discrepancies between the model and observations could point to missing physics in current theories.

Julian Muñoz, an assistant professor of astronomy at the University of Texas at Austin who was not involved in the study, described Lumina as a technical achievement that expands both the spatial scale and the simulated cosmic time compared with earlier models. He added that the simulation’s size allows scientists to examine how ordinary matter and dark matter moved differently and to investigate rare galaxies that smaller simulations may overlook.

Ilian Iliev, a professor of astrophysics at the University of Sussex, said he looks forward to combining Lumina’s results with new telescope data to improve the overall picture of early cosmic evolution.