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Simulation indicates stars and black holes drove early universe reionization

Scientific American reports that the Lumina simulation models a two-billion-year early-universe era across more than 1.5 billion light-years.

Published Nov 13, 2026 · 15:03 UTC1 reports

The short version

  • Researchers published initial results from the Lumina simulation on October 26 in the Monthly Notices of the Royal Astronomical Society.[Scientific American]
  • The simulation models a volume over 1.5 billion light-years wide across a two-billion-year era beginning about 50 million years after the big bang.[Scientific American]
  • The model indicates stars and supermassive black holes both drove reionization, with black holes fully ionizing helium; magnetic effects are not included.[Scientific American]
  • Hydrogen reionization finished about 12.5 billion years ago, and helium reionization ended about 1.2 billion years after starting around 12.8 billion years ago.[Scientific American]

Key facts

  • Researchers published initial Lumina results on October 26 in the Monthly Notices of the Royal Astronomical Society.[Scientific American]
  • Lumina covers a volume more than 1.5 billion light-years wide, with resolution down to about 1,400 light-years.[Scientific American]
  • Lumina divides its volume into 432 billion individual sectors.[Scientific American]
  • Lumina covers a two-billion-year period starting about 50 million years after the big bang.[Scientific American]
  • Lumina does not include magnetic effects.[Scientific American]
  • The simulation indicates stars drove hydrogen ionization and removed one electron from helium, while black holes fully ionized helium.[Scientific American]
  • According to the simulation, hydrogen reionization completed about 12.5 billion years ago.[Scientific American]
  • Helium reionization started around 12.8 billion years ago and finished about 1.2 billion years later.[Scientific American]

What remains uncertain

  • The findings come from a simulation and are initial results, not direct observations, and the reporting does not describe independent replication.[Scientific American]
  • The model excludes magnetic effects, which the reporting describes as complex and difficult to calculate, so their influence on the results is unaddressed.[Scientific American]

Sources

Outlet counts describe coverage, not independent confirmation. Reports may share a wire service or original source.