Lumina simulation traces how early stars and black holes changed cosmic gas

A new computer simulation called Lumina follows how galaxies, stars and active black holes changed the gas between galaxies during the early universe. Researchers describe the project in Monthly Notices of the Royal Astronomical Society, modelling both hydrogen and helium reionization within one large cosmological volume.

Reionization is the process in which energetic radiation removes electrons from atoms. In the study, light from stars drives most hydrogen reionization, while radiation associated with active galactic nuclei drives the later helium transition. Following those processes together helps researchers test how the sources of light and surrounding gas influenced one another as galaxies developed.

The model covers a volume with a comoving side length of 500 megaparsecs. It combines a galaxy-formation model with GPU-accelerated radiation transport, tracking ordinary matter, dark matter and radiation. The researchers report broad agreement with several observational constraints, while the large volume is intended to improve the study of rare objects and differences between cosmic regions.

Lumina is a model for comparison with observations, not a direct recording of the young universe. Published reporting indicated on November 11 that astronomers expect such simulations to complement observations from telescopes including James Webb. Agreement can support a model's assumptions; disagreements can help identify where the physics or its treatment needs further work. The accompanying archive sky photograph is illustrative and does not show the simulation.