New cutting-edge simulations by Maynooth University astronomers have shown that at the dawn of the dense, turbulent universe, “light seed” black holes could rapidly gobble up matter, rivaling the supermassive black holes seen at the centers of early galaxies.
Computer visualization showing a baby black hole growing in a young galaxy in the early universe. Image credit: Maynooth University.
“We found that the chaotic conditions that existed in the early universe gave rise to earlier smaller black holes that, after a feeding frenzy that devoured the surrounding matter, later grew into the supermassive black holes we see,” said Dr. Daksar Mehta. candidate at Maynooth University.
“Using cutting-edge computer simulations, we show that the first generation of black holes, which were born just a few hundred million years after the Big Bang, grew at incredible speeds, reaching tens of thousands of times the size of the Sun.”
Dr Louis Prowl, a postdoctoral researcher at Maynooth University, said: “This groundbreaking discovery solves one of the great mysteries of astronomy.”
“This is how black holes born in the early universe were able to rapidly reach such supermassive sizes, as observed by NASA/ESA/CSA’s James Webb Space Telescope.”
The dense, gas-rich environment of early galaxies enabled short bursts of “super-Eddington accretion.” A term used to describe what happens when a black hole “eats” matter faster than normal or safe.
It’s so fast that the light should blow the food away, but it still manages to keep eating.
The results revealed a “missing link” between the first stars and the supermassive black holes that appeared much later.
“These small black holes were previously thought to be too small to grow into the massive black holes observed at the centers of early galaxies,” Mehta said.
“What we have shown here is that although these nascent black holes are small, given the right conditions they can grow surprisingly fast.”
There are two types of black holes: “heavy seed” and “light seed” types.
Light seed types are relatively small to begin with, at most only about 10 to a few hundred times the mass of the Sun, and must grow from there to become “supermassive,” or millions of times the mass of the Sun.
The heavy type, on the other hand, already starts life with a much larger mass, perhaps up to 100,000 times the mass of the Sun at birth.
Until now, astronomers thought that a type of heavy species was needed to explain the existence of the supermassive black holes found at the centers of most large galaxies.
Dr John Regan, an astronomer at Maynooth University, said: “Now we’re not too sure.”
“Heavy seeds are somewhat exotic and may require unusual conditions to form.”
“Our simulations show that ‘garden-type’ stellar-mass black holes can grow at extreme rates in the early universe.”
This research not only reshapes our understanding of the origin of black holes, but also highlights the importance of high-resolution simulations in unraveling the universe’s earliest secrets.
“The early universe was much more chaotic and turbulent than we expected, and there is also a much larger population of supermassive black holes than we expected,” Dr. Regan said.
The results also have implications for the ESA/NASA Laser Interferometer Space Antenna (LISA) mission, scheduled to launch in 2035.
“Future gravitational wave observations from this mission may detect mergers of these small, early, rapidly growing baby black holes,” Dr. Regan said.
a paper The findings were published in this week’s magazine natural astronomy.
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DH meter others. Growth of light seed black holes in the early universe. Nat Astronpublished online on January 21, 2026. doi: 10.1038/s41550-025-02767-5