Cosmologists have linked observations of the earliest galaxies with the chemical makeup of ancient stars in the Milky Way using MEGATRON, a high-resolution early-universe simulation suite. Researchers announced the findings across four papers published on 30 September 2026 in the Open Journal of Astrophysics, providing a new physical framework to study stellar evolution.
The universe started with a simple recipe. Shortly after the Big Bang, space was filled with pristine gas made entirely of hydrogen and helium, containing no heavy elements at all. Leading scientific models generally suggest that the initial population of stars came into existence somewhere between 100 million and 400 million years following the Big Bang. Into this dark expanse emerged the universe’s first generation of stars, known as Population III stars. These ancient bodies lit up the cosmos during its infancy, and when they eventually detonated as supernovae, they scattered newly forged heavy elements—such as carbon, oxygen, and iron—into the surrounding space. Those scattered metals became the essential building blocks for subsequent star formation, planetary systems, and ultimately life.
Scientists have long sought to trace how those pristine clouds transformed into the chemically rich cosmos seen today. To researchers and cosmologists, the Cosmic Dark Ages represent the final frontier, containing the keys to understanding the development and growth of the earliest stars and galaxies. Two distinct observational windows have offered clues: the James Webb Space Telescope (JWST), which peers directly at young galaxies in the infant universe, and stellar archaeology, which studies the ancient stellar relics preserved right inside our own galactic neighborhood. Until now, connecting these two datasets proved exceptionally difficult.
To bridge the gap between distant galaxy observations and local stellar fossils, an international team led by researchers at the University of Bath developed MEGATRON. The project combines advanced cosmological simulations with sophisticated computer models that simultaneously track gas motion, starlight propagation, and chemical concentrations over billions of years.
In addition to the University of Bath, the international collaboration includes researchers from the University of Chicago in the US and the Institut d’Astrophysique de Paris in France.
“The elements that make our world and life possible – carbon, oxygen, iron and many others – were forged by stars. To understand where those elements came from, we need to understand how the first stars formed and enriched their surroundings, MEGATRON allows us to test these ideas directly by comparing detailed simulations with observations from JWST and the chemical fingerprints preserved in ancient stars.”
Martin Rey, Department of Physics at the University of Bath
The collaboration published its first substantial body of results on 30 September 2026 in the Open Journal of Astrophysics, detailing findings across four separate papers.
Supercomputer Simulations Reveal How Stellar Radiation Shapes Early Galaxies
The simulation followed a young galaxy from its earliest gas clouds to a system projected to grow into a mass comparable to the Milky Way. By running models at exceptionally high resolution, the research team discovered that simpler computer simulations may underestimate how strongly stellar radiation and complex chemical processes reshape the gas surrounding early galaxies.
The results indicate that the interplay between starlight, gas, and newly forged elements connects what the JWST sees in deep space with the chemical signatures embedded in ancient Milky Way stars. The high-resolution approach successfully resolved gas structures that standard models consistently miss.
“The James Webb Space Telescope gives us a direct glimpse of the infant cosmos, while stellar archaeology allows us to study the relics of those earliest times in our own Galactic neighborhood. MEGATRON provides a physical bridge between the two.”
Dr. Martin Rey, Department of Physics at the University of Bath
National Supercomputer Allocation Funds Future Modeling Work
The MEGATRON project, which originally began in 2023, is scheduled to run until 2030.
With these expanded resources, researchers plan to run higher-resolution simulations featuring more complete physical models. This increased power will allow scientists to compare theoretical models even more directly against ongoing JWST observations and large-scale astronomical surveys mapping ancient stars.
“MEGATRON provides a common physical framework for interpreting two of astronomy’s most exciting new datasets: JWST’s view of the earliest galaxies and the stellar fossil record. Together, these complementary observations allow us to test competing models of the first stars in ways that weren’t previously possible.”
Dr Martin Rey, University of Bath
By integrating these diverse data sources, the new framework enables a more precise understanding of how the earliest stars and galaxies shaped the evolution of the early universe.