Researchers at MIT, Harvard University, and other institutions have developed Lumina, a computer simulation that recreates the evolution of the early universe across a region roughly 1.6 billion light-years wide over 2 billion years of cosmic history. The simulation follows how galaxies formed, how radiation spread through space, and how the universe became transparent to light after emerging from the cosmic dark age.
Lumina covers a volume 500 megaparsecs wide and contains approximately half a trillion individual elements, including dark matter particles and gas cells. It provides roughly 30 times the resolution of IllustrisTNG, an earlier simulation, while covering a region 100 times larger in volume than previous leading simulations. The researchers used Frontier, one of the world's most powerful supercomputers at Oak Ridge National Laboratory in Tennessee, to perform the calculations.
The simulation recreates two major transformations in the early universe. Hydrogen re-ionization began as the first stars and galaxies produced ultraviolet radiation that removed electrons from neutral hydrogen atoms, making the universe increasingly transparent to ultraviolet light. Helium re-ionization required substantially more energetic radiation to strip electrons from helium. The results indicate that early stars and galaxies were primarily responsible for ionizing hydrogen, while actively feeding supermassive black holes supplied the intense radiation needed to ionize helium.
"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 Mark Vogelsberger, a professor of physics at MIT.
The research was published in the Monthly Notices of the Royal Astronomical Society. Researchers have made Lumina available to other scientists, allowing its predictions about early cosmic structures to be compared with observations from existing and future telescopes.