A new computer simulation called Lumina, developed by researchers at MIT, Harvard University, and other institutions, recreates the early universe across a region roughly 1.6 billion light-years wide, following 2 billion years of cosmic history to show how the first stars and galaxies transformed the cosmos from darkness to transparency. The research, published in the Monthly Notices of the Royal Astronomical Society, provides an unusually detailed picture of hydrogen and helium reionization, capturing both processes together for the first time.
Lumina begins approximately 45 million years after the Big Bang, during an era when neutral hydrogen dominated the universe in what is known as the cosmic 'dark age.' Before stars formed, neutral hydrogen filled space and could absorb ultraviolet light. The simulation covers an immense volume of 500 megaparsecs, equivalent to about 1.6 billion light-years, and follows dark matter, gas, stars, and radiation over 2 billion years.
It reproduces two key transformations: hydrogen reionization, driven by ultraviolet radiation from early stars and galaxies that stripped electrons from hydrogen atoms, making the universe increasingly transparent to ultraviolet light; and helium reionization, which requires more energetic radiation and appears to have been driven by actively feeding supermassive black holes. This is the first simulation to capture both processes together.
'Lumina does everything from small-scale star and galaxy formation to large-scale reionization of hydrogen and helium, in a volume that is 100 times larger than previous best simulations,' says study author Mark Vogelsberger, a professor of physics at MIT.
To create Lumina, researchers upgraded existing software used for the earlier IllustrisTNG simulation and incorporated a radiation transport model. The resulting model contains approximately half a trillion individual elements, including dark matter particles and gas cells, providing roughly 30 times the resolution of IllustrisTNG while covering a region 100 times larger in volume than previous leading simulations. It was run on Frontier, a supercomputer at Oak Ridge National Laboratory in Tennessee.
'At peak scale, the calculation brings together the equivalent of more than 100,000 CPU cores and around 15,000 GPUs,' says Xuejian (Jacob) Shen, an MIT co-author. The simulation allows researchers to zoom from the full volume down to individual galaxies, tracking how radiation from stars travels out through the universe and ionizes neutral hydrogen.
The team plans to use Lumina to investigate the large-scale arrangement of matter in the early universe. The simulation could also help predict gravitational wave patterns. Comparisons with real observations from new telescopes could test understanding of early cosmic structures. 'One of Lumina's major advantages is its sheer size,' Shen says. 'It produces enormous populations of simulated galaxies, finally allowing us to make comparisons with the very large galaxy samples that upcoming surveys will observe.'
Analysis
Why This Matters
- Offers a detailed virtual model of the universe's first 2 billion years, a period previously difficult to simulate at this scale and resolution
- Combining hydrogen and helium reionization in one simulation may resolve questions about what drove the universe's transformation from opaque to transparent
- Provides a testbed for upcoming telescopes, potentially confirming or challenging current theories of galaxy formation
Background
The cosmic dark age began about 380,000 years after the Big Bang, when the universe had cooled enough for electrons to combine with atomic nuclei to form neutral hydrogen. Without stars, the universe was dark and opaque to ultraviolet light. The first stars and galaxies eventually formed, emitting radiation that reionized hydrogen and later helium, making the universe transparent. Earlier simulations either covered smaller volumes or lacked the radiation transport needed to model reionization; Lumina is the first to combine high resolution with a very large volume and full radiation physics.
Key Perspectives
Researchers (MIT, Harvard, and other institutions): Say Lumina provides the most comprehensive simulation yet of the early universe, capturing both small-scale galaxy formation and large-scale reionization in a volume 100 times larger than previous leading simulations. They plan to compare its predictions with observations from new telescopes.
What to Watch
- Whether upcoming telescope surveys match Lumina's predictions for the number and distribution of early galaxies
- Further analysis of the simulation's predictions for gravitational waves from ancient black holes
- Applications of the simulation's code to other questions in cosmology
Checked
12 claims in this story checked against 1 source: 12 supported.
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- SupportedThe headline says a massive new simulation reveals the universe’s emergence from darkness.Latest Science News -- ScienceDaily: “A massive new simulation reveals how the universe emerged from darkness.”
- SupportedLumina recreates the early universe across a region roughly 1.6 billion light-years wide.Latest Science News -- ScienceDaily: “the simulation, called Lumina, recreates the evolution of the early universe across a region roughly 1.6 billion light-years wide.”
- SupportedLumina follows 2 billion years of cosmic history.Latest Science News -- ScienceDaily: “It follows 2 billion years of cosmic history, revealing how galaxies formed, how radiation spread through space, and how the universe gradually became transparent to light.”
- SupportedThe simulation captures hydrogen and helium reionization together for the first time.Latest Science News -- ScienceDaily: “This is the first simulation to capture both processes together, offering a more complete view of how the early universe changed.”
- SupportedMark Vogelsberger said: “Lumina does everything from small-scale star and galaxy formation to large-scale reionization of hydrogen and helium, in a volume that is 100 times larger than previous best simulations,”Latest Science News -- ScienceDaily: “"Lumina does everything from small-scale star and galaxy formation to large-scale reionization of hydrogen and helium, in a volume that is 100 times larger than previous best simulations," says study author Mark Vogelsberger, a professor of physics at MIT.”
- SupportedLumina begins approximately 45 million years after the Big Bang.Latest Science News -- ScienceDaily: “Lumina begins approximately 45 million years after the Big Bang, during an era when neutral hydrogen dominated the universe.”
- SupportedEarly stars and galaxies produced ultraviolet radiation that drove hydrogen reionization.Latest Science News -- ScienceDaily: “Hydrogen re-ionization began as the first stars and galaxies produced increasing amounts of ultraviolet radiation.”
- SupportedActively feeding supermassive black holes appear to have supplied the radiation needed for helium reionization.Latest Science News -- ScienceDaily: “Early stars and galaxies appear to have been primarily responsible for ionizing hydrogen, while actively feeding supermassive black holes supplied the intense radiation needed to ionize helium.”
- SupportedThe model contains approximately half a trillion individual elements, including dark matter particles and gas cells.Latest Science News -- ScienceDaily: “The resulting model contains approximately half a trillion individual elements, including particles of dark matter and cells representing gas.”
- SupportedLumina provides roughly 30 times the resolution of IllustrisTNG.Latest Science News -- ScienceDaily: “It provides roughly 30 times the resolution of IllustrisTNG while covering a region 100 times larger in volume than previous leading simulations.”
- SupportedXuejian (Jacob) Shen said: “At peak scale, the calculation brings together the equivalent of more than 100,000 CPU cores and around 15,000 GPUs,”Latest Science News -- ScienceDaily: “"At peak scale, the calculation brings together the equivalent of more than 100,000 CPU cores and around 15,000 GPUs," says Xuejian (Jacob) Shen, an MIT co-author of the study.”
- SupportedShen said: “One of Lumina's major advantages is its sheer size. It produces enormous populations of simulated galaxies, finally allowing us to make comparisons with the very large galaxy samples that upcoming surveys will observe.”Latest Science News -- ScienceDaily: “"One of Lumina's major advantages is its sheer size," Shen says. "It produces enormous populations of simulated galaxies, finally allowing us to make comparisons with the very large galaxy samples that upcoming surveys will observe."”