New cosmological simulations from Maynooth University astronomers demonstrate that small “light seed” black holes in the early universe could have grown exceptionally quickly, potentially explaining how supermassive black holes formed so soon after the Big Bang. This research addresses a long-standing puzzle in astronomy: how black holes evolved to immense sizes in a relatively short period.
The Feeding Frenzy of Early Black Holes
The simulations depict a chaotic early universe, where dense and turbulent conditions allowed smaller black holes to rapidly consume surrounding matter. According to Ph.D. candidate Daxal Mehta, these environments triggered what researchers call “super Eddington accretion” – an accelerated rate of consumption where black holes ingest material faster than theoretically possible.
The simulations revealed that the first generation of black holes, born just a few hundred million years after the Big Bang, could grow into sizes tens of thousands of times that of our Sun.
This rapid growth resolves a key question raised by observations from the James Webb Space Telescope: how did early black holes reach such massive sizes so quickly?
Light Seeds vs. Heavy Seeds
Black holes are categorized into two types: “heavy seeds” and “light seeds”. Heavy seeds are already massive at birth, potentially reaching hundreds of thousands of times the mass of the Sun. Light seeds, on the other hand, begin much smaller (ten to a few hundred solar masses) and must grow to become supermassive.
For years, astronomers believed that heavy seeds were essential for explaining the presence of supermassive black holes at the centers of galaxies. However, Maynooth University’s research suggests that “garden variety” stellar mass black holes can grow at extreme rates in the early universe, given the right conditions.
Implications for Future Research
The findings reshape our understanding of black hole origins and highlight the importance of high-resolution simulations in cosmology. The early universe appears far more chaotic than previously thought, with a larger population of massive black holes than anticipated.
This research also has implications for the upcoming ESA/NASA Laser Interferometer Space Antenna (LISA) mission, scheduled for launch in 2035. LISA may detect gravitational waves from the mergers of these early, rapidly growing black holes, providing further evidence for the simulations’ findings.
The study was published in Nature Astronomy on January 21, 2026. The results confirm that the early universe was a turbulent period of rapid black hole growth, where even small seeds could become galactic behemoths.
