Milky Way Formed From Thousands of Galaxies

Researchers at the MEGATRON project used detailed simulations to study how the first stars and galaxies formed. The team, led by researchers from the University of Bath and the University of Chicago, created simulations that connected observations of the early Universe with the chemical fingerprint of the oldest stars in the Milky Way.

The simulations began with conditions present shortly after the Big Bang and tracked the evolution of a young galaxy over billions of years. The team included advanced computer models that tracked gas movement, starlight propagation, and the evolution of chemical concentrations.

Dr. Martin Rey from the University of Bath said the MEGATRON project provides a common physical framework for interpreting new datasets from the James Webb Space Telescope and the stellar fossil record. This allows scientists to test competing models of the first stars in ways that weren't previously possible.

The MEGATRON project began in 2023 and is scheduled to run until 2030. The team's findings were presented in four papers published in the Open Journal of Astrophysics. The simulations show the connection between observations of the early Universe and the chemical fingerprint of the oldest stars in the Milky Way.

Harley Katz, assistant professor of astronomy and astrophysics at the University of Chicago, said the simulations can directly predict what the early Milky Way would have looked like to telescopes like Hubble or the James Webb Space Telescope. The team's work provides new insight into the makeup of early galaxies and how the elements formed over time.

The first stars transformed a Universe made mostly of hydrogen and helium, scattering newly forged elements that later became part of stars, planets, and eventually life. The MEGATRON project links galaxies observed by the James Webb Space Telescope with chemical signatures preserved in ancient stars in and around the Milky Way.

The simulations took three years to run on high-powered supercomputers and are the most detailed model to date of how a galaxy like the Milky Way might have evolved over the first several billion years of its existence. The team's work will help astronomers reconstruct how the first stars formed and spread new elements through space.