One of astronomy’s biggest mysteries has long puzzled scientists: how did black holes grow so enormous so quickly after the universe was born?
New research from Maynooth University in Ireland may finally provide a clear answer.
According to a study published in Nature Astronomy, researchers found that the chaotic conditions of the early universe allowed small, newly formed black holes to grow at astonishing speeds.
Instead of slowly gaining mass over billions of years, these early “baby” black holes went through intense growth spurts that rapidly turned them into the supermassive black holes seen at the centers of galaxies today.
The research was led by Daxal Mehta, a PhD candidate in the Department of Physics at Maynooth University.
Using advanced computer simulations, Mehta and his colleagues showed that the first generation of black holes—formed just a few hundred million years after the Big Bang—could grow to tens of thousands of times the mass of the Sun in a surprisingly short time.
“This helps solve one of the biggest puzzles in astronomy,” said Dr. Lewis Prole, a postdoctoral researcher on the team.
Recent observations from the James Webb Space Telescope have revealed enormous black holes in the very early universe, and until now, scientists struggled to explain how they formed so fast.
The key lies in the extreme environments of early galaxies. Back then, galaxies were packed with dense clouds of gas. These conditions allowed black holes to enter short periods of runaway feeding, known as “super-Eddington accretion.” In simple terms, this means the black hole consumed matter faster than what was once thought physically possible. Normally, the intense light released during feeding should push material away, slowing growth. But in the early universe, black holes somehow kept eating despite this limit.
This finding bridges a long-standing gap between the first stars and the giant black holes that appeared later. Until now, many astronomers believed that only “heavy seed” black holes—born already extremely massive—could explain the presence of supermassive black holes so early in cosmic history. These heavy seeds are thought to form under rare and unusual conditions.
The new study challenges that idea. It shows that “light seed” black holes, which form from collapsing stars and start out only a few to a few hundred times the mass of the Sun, can also grow incredibly fast if the environment is right. This suggests that ordinary stellar black holes may have been far more important in shaping the early universe than previously believed.
The results also point to a much more chaotic and turbulent early universe, filled with rapidly growing black holes. This has exciting implications for future space missions, including the planned Laser Interferometer Space Antenna (LISA), a joint ESA-NASA mission scheduled for launch in 2035.
LISA may be able to detect gravitational waves from mergers between these early, fast-growing black holes, offering a new way to test these findings and deepen our understanding of how the universe’s largest black holes came to be.
Source: KSR.
