The Lumina simulation represents the largest computational model of cosmic radiation hydrodynamics, covering a volume more than 100 times greater than previous simulations by running on more than 15,000 GPUs on the Frontier supercomputer.
Lumina cosmic simulation launched to match modern telescope observations
Standard-size cosmic cube and unprecedented modeling of helium reionization
Supercomputing behind the model and cosmic microwave background radiation effects
Testing platform for new telescopes and the future of star formation studies
FAQs
Lumina cosmic simulation launched to match modern telescope observations
Researchers at the Center for Astrophysics | Harvard & Smithsonian have launched the “Lumina” project, described by the Smithsonian Institution as the largest cosmic radiation hydrodynamics simulation ever developed. This physical model rebuilds how ordinary matter, dark matter, and cosmic radiation interacted during the first two billion years of the universe’s history.
The results of this scientific work were published in the journal Monthly Notices of the Royal Astronomical Society. The simulation provides astronomers with an accurate reference tool to test and compare astronomical observations from the James Webb Space Telescope, the Nancy Grace Roman Space Telescope, and other advanced observational tools against theoretical predictions. When a conflict arises between observation and simulation, it may necessitate revising current theories of cosmic evolution.
Standard-size cosmic cube and unprecedented modeling of helium reionization
The “Lumina” simulation covers a volume exceeding 100 times the size of previous similar simulations, extending across a region shaped like a cube with sides measuring approximately 1.5 billion light-years—roughly equivalent to the range that today’s most powerful telescopes can observe. The team’s technical description sets the size of the cosmic box at about 500 comoving parsecs per side, with a computational resolution of 2 multiplied by 6,000 cubed resolution elements, encompassing gas cells alongside dark matter particles.
The model tracks the interconnected evolution of galaxies, black holes, and intergalactic gas through the phases of hydrogen and helium reionization. According to the researchers, Lumina is the first simulation to model helium reionization as it occurs while allowing its physical effects to provide immediate feedback within the evolving model universe, noting that reionization is the phase where ultraviolet rays emitted by the first stars and growing black holes stripped atoms of their electrons so that ionized regions spread and merged like bubbles.
Aaron Smith, assistant professor of physics at the University of Texas at Dallas and co-author of the study, said: “For the first time, we can follow step-by-step as both hydrogen and helium transform into their modern forms across this vast volume of the universe, while continuing to analyze the galaxies and other luminous objects driving this transformation.”
Supercomputing behind the model and cosmic microwave background radiation effects
The simulation was run across more than 15,000 GPUs on the “Frontier” supercomputer—one of the world’s fastest supercomputers—at the Oak Ridge National Laboratory in Tennessee, USA. This immense computational power allowed the team to model a remarkably massive cosmic volume while maintaining enough fine detail to study how galaxies, stars, and black holes form.
The project has already yielded follow-up scientific research; an initial study published in May 2026 led by Smith used Lumina data to calculate how heterogeneous reionization affects the cosmic microwave background radiation, finding that the optical depth calculated as an average along lines of sight was about 7% higher than the value deduced from volume-weighted cosmic history.
Testing platform for new telescopes and the future of star formation studies
The scientific team designed the Lumina model to be an open platform for testing cosmic hypotheses, with future studies focusing on how gas moves between galaxies and how regions undergoing intense rates of new star birth evolve.
Oliver Zier, lead author of the study and a fellow at the Institute for Theory and Computation at the center, said: “With the James Webb Space Telescope, the early universe has become an exciting new scientific frontier in astrophysics. After several years of work filled with many challenges and successes, it is very rewarding to see the simulation results and watch our predictions come to life in the videos.”
FAQs
Question: What is the Lumina simulation launched by the Harvard and Smithsonian center?
Answer: It is the largest cosmic radiation hydrodynamics simulation ever created, reconstructing the interaction of ordinary matter, dark matter, and radiation during the first two billion years of the universe’s life.
Question: What is the size of the cosmic region covered by the Lumina simulation compared to previous simulations?
Answer: The simulation covers a cube with a side length of about 1.5 billion light-years—more than 100 times the size of previous similar simulations—with a resolution of 2 multiplied by 6,000 cubed elements.
Question: Where was the Lumina simulation run and what computational power was used?
Answer: It was run on more than 15,000 GPUs on the Frontier supercomputer at the Oak Ridge National Laboratory in Tennessee, USA.
Question: What unique physical achievement did Lumina provide in the study of reionization?
Answer: It is the first simulation to model helium reionization as it happens while allowing its effects to provide immediate feedback in the evolving universe, showing an approximately 7% increase in the optical depth of background radiation.
