See and hear galaxies evolving in these new simulations. Video via Royal Astronomical Society.
- New simulations let scientists see and hear galaxy evolution. The COLIBRE simulations trace growth from the early universe to today in unprecedented detail.
- By including cold gas and cosmic dust – the raw materials for stars – the models more accurately reproduce real galaxies. The simulations match observations from telescopes like Webb.
- The results show the standard cosmological model still holds up. They also explain how galaxies formed and evolved over billions of years to the present day.
The Royal Astronomical Society published this original story on April 13, 2026. Edits by EarthSky.
Modeling how galaxies grow and evolve
Scientists have created the most realistic simulations yet of how galaxies formed and changed over time. These simulations let us both see and even hear how galaxies evolved in the early universe.
The Monthly Notices of the Royal Astronomical Society published the data on April 13, 2026. It shows that the standard cosmological model can successfully explain the observed growth of galaxies, from the first billion years after the Big Bang to the present day, when key physics is included.
Unlike earlier simulations, the COLIBRE virtual universes model the cold gas and cosmic dust inside galaxies. That’s the raw materials from which stars form. And it strongly affects how galaxies look in telescopes.
By including these previously missing ingredients and using far more computing power than ever before, the simulations successfully reproduce real galaxies. And it can do so both in the present-day universe and in the early universe that the James Webb Space Telescope has witnessed.
Project leader Joop Schaye of Leiden University said:
Much of the gas inside real galaxies is cold and dusty, but most previous large simulations had to ignore this. With COLIBRE, we finally bring these essential components into the picture.
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Digital cold gas and dust grains
According to the international team of researchers, their COLIBRE simulations break new ground in several ways. Earlier simulations artificially prevented gas inside galaxies from cooling below about 10,000° Fahrenheit (5,500 C). That’s hotter than the surface of the sun. Previously, modeling colder gas was too complex. And yet, observations show that stars form in cold gas. COLIBRE includes the additional physical and chemical processes needed to model this cold interstellar gas directly.
COLIBRE also simulates small dust grains. These grains can greatly influence galactic gas. The solid particles can help hydrogen molecules to form, which dominate the cold gas content of galaxies. The dust also shields gas from harsh ultraviolet radiation. And it strongly affects how galaxies appear in telescopes. Dust absorbs ultraviolet and optical light from stars and re-emits it in the infrared, shaping many astronomical observations. By modeling dust directly, COLIBRE opens new ways to compare simulations with real data.
Thanks to advances in algorithms and supercomputing, COLIBRE uses up to 20 times more resolution elements than earlier simulations. And this allows scientists to simulate larger volumes in greater detail and with better statistics.
A new laboratory
COLIBRE demonstrates that realistic treatments of cold gas, dust and outflows driven by stars and black holes are crucial for understanding galaxy evolution, the researchers say. It provides a powerful new laboratory for testing theories, interpreting observations and creating “virtual observations” to check how astronomers analyze real data.
The findings also show the standard cosmological model remains consistent with observations of galaxy evolution. And that includes some scientists thought were challenging, such as the masses of galaxies in the early universe.
Evgenii Chaikin of Leiden University is lead author of several accompanying COLIBRE papers and co-author of the main study. Chaikin said:
Some early JWST results were thought to challenge the standard cosmological model. COLIBRE shows that, once key physical processes are represented more realistically, the model is consistent with what we see.
Some questions remain
Still, not everything has been explained yet, such as the Webb-discovered enigmatic Little Red Dots. These are possibly seeds of supermassive black holes, which COLIBRE didn’t predict. So it assumes such seeds already exist. Modeling their formation will require even higher resolution simulations and new physics.
Astronomers ran the simulations using the SWIFT simulation code on the COSMA8 supercomputer at the Institute for Computational Cosmology at Durham University. This is hosted on behalf of the DiRAC national facility in the UK. The largest simulation required 72 million CPU hours, and the full model took nearly 10 years to develop by an international team spanning Europe, Australia and the United States.
Carlos Frenk is the Ogden Professor of Fundamental Physics at the Institute for Computational at Durham University and a core member of the COLIBRE team. Frenk said:
It is exhilarating to see ‘galaxies’ come out of our computer that look indistinguishable from the real thing and share many of the properties that astronomers measure in real data such as their number, luminosities, colors and sizes.
I like to tease my observer colleagues by asking ‘which galaxy catalogue do you think these images came from?’
What is most remarkable is that we are able to produce this synthetic universe purely by solving the relevant equations of physics in the expanding universe.
The scientists point out that it will take years to analyze the data already produced. Most simulations were completed in 2025, although some of the simulations with the highest resolution are still running. The researchers expect to finish them after the summer.
See and hear galaxies evolve
Beyond traditional data products, the team has developed new ways to explore the simulations. This includes sonified videos. The videos have sound encoded for additional physical information. They also have interactive maps that allow users to explore the virtual universes.
James Trayford of the University of Portsmouth led the development of COLIBRE’s dust model and the sonification of its visualizations. Trayford said:
We’re excited not just about the science, but also about creating new ways to explore it. These tools could provide new insights, make our field more accessible, and help us build intuition for how galaxies grow and evolve.
Bottom line: See and hear galaxies evolving in new simulations with this video from the Royal Astronomical Society. The simulations help astronomers trace growth from the early universe to today.
Source: The COLIBRE project: cosmological hydrodynamical simulations of galaxy formation and evolution
Via Royal Astronomical Society