Irish physicists make ‘Renaissance’ simulation of early universe

27 Oct 2023

Image: © pongpinun/

Lead author of the study Joe McCaffrey said that the simulations, which corroborate findings from JWST, help us understand the origins of the universe.

Physicists based at Maynooth University have developed a series of sophisticated computer simulations of the early universe that can help us better understand the formation of galaxies.

The so-called Renaissance simulations show that observations made by the James Webb Space Telescope on the early universe are consistent with theoretical expectations.

Initial observations made by the James Webb hinted at a possible gap in our theoretical understanding of early galaxy formation, because the first galaxies seen through the telescope appeared to be brighter and more massive than expected.

The study was conducted with collaborators at Georgia Institute of Technology in the US and findings were published in the Open Journal of Astrophysics.

Maynooth University said in a statement that the simulation can resolve very small “dark matter clumps” and track them as they coagulate and build up as dark matter “halos” which then host the types of galaxies that we observe.

Showing that these galaxies are consistent with models that dictate the physics of the cosmological simulations, the simulations also modelled the formation of the very first stars that formed in our universe, called Population III stars. These stars are expected to be much more massive and brighter than present-day stars.

“The James Webb Space Telescope has revolutionised our understanding of the early universe,” said Dr John Regan, who is an associate professor at Maynooth’s Department of Theoretical Physics.

“Using its incredible power, we are now able to glimpse the universe as it was only a few hundred million years after the Big Bang – a time when the universe was less than 1pc of its current age.

“What [the James Webb] is showing us is that the young universe was bursting with massive star formation and an evolving population of massive black holes. The next steps will be to use these observations to guide our theoretical models – something which up until very recently was simply impossible.”

Joe McCaffrey, lead author of the paper published on the study and a PhD researcher at Maynooth, said that the simulations are “crucial” in understanding our origin in the universe.

“In future, we hope to use these same simulations to investigate the growth of massive black holes in the early universe.”

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Vish Gain is a journalist with Silicon Republic