Updated by FFRNews on November 5, 2025
Astronomers have long wondered how the early universe helps black holes grow so large, so fast. At the center of our Milky Way lies a supermassive black hole about four million times the mass of the Sun, but others—like the one in galaxy M87—are billions of times heavier. Even more puzzling are the young black holes discovered by the James Webb Space Telescope (JWST) in some of the earliest galaxies ever seen. These cosmic giants existed when the universe was less than a billion years old, yet they already weighed more than a billion Suns.
The Mystery of Supermassive Growth
Conventional models suggest black holes grow over billions of years by merging with others and slowly swallowing matter. As galaxies collide and combine, their central black holes also merge, forming even larger ones. But that process takes time—far too much to explain the titanic black holes seen so early in cosmic history.
If the early universe helps black holes grow faster, what changed back then? Scientists now think the answer lies in a brief, intense phase of accelerated growth.
Breaking the Eddington Limit
Normally, black holes can only grow at a pace determined by the Eddington Limit. This natural threshold occurs because as matter falls toward a black hole, it heats up and emits powerful radiation that pushes new material away. It’s a cosmic balance—too much radiation, and the black hole can’t eat any faster.
But new research from Ziyong Wu, Renyue Cen, and Romain Teyssier, published on arXiv, suggests the Eddington Limit might not have applied in the same way during the early universe. Their simulations of the cosmic dark age—the period after atoms formed but before the first stars ignited—show that extreme densities allowed black holes to grow beyond today’s physical limits.
Super-Eddington Growth: A Cosmic Shortcut
During these conditions, material around black holes was so thick that the hot plasma couldn’t escape easily. This trapped energy let the black holes feed much faster than normal, entering what scientists call super-Eddington growth. According to the study, this allowed early black holes to reach about 10,000 solar masses relatively quickly.
However, this rapid growth didn’t last long. Once surrounding material thinned, the Eddington Limit reasserted itself, slowing their growth dramatically. Over time, black holes that started fast and those that grew slowly reached roughly the same sizes—like a sprinter being overtaken by a marathon runner.
Why It Still Doesn’t Explain Everything
Even with this burst of early feeding, super-Eddington growth can’t fully explain the billion-solar-mass monsters JWST has observed in galaxies less than 700 million years old. The study concludes that while the early universe helps black holes grow quickly at first, something else must have given them a head start.
One leading theory involves primordial seed black holes—objects that formed directly from massive gas clouds or perhaps even during the inflationary period right after the Big Bang. These seeds could have started with much higher masses, giving them a running start in their race toward becoming supermassive.
Implications for Modern Astronomy
Understanding how the early universe helps black holes grow isn’t just about cosmic history—it’s about physics itself. If supermassive black holes really formed so early, that challenges long-standing theories about gravity, dark matter, and galaxy evolution.
Researchers hope that upcoming JWST observations and next-generation telescopes will uncover even more examples of early black holes, helping to refine models of how they form and evolve. Each new discovery reshapes our understanding of how the universe built its first colossal structures.
A New Window into the Cosmos
This new study highlights just how dynamic and mysterious the early cosmos was. It shows that while the early universe helps black holes grow big, nature has built-in limits to prevent endless acceleration. These insights bring scientists closer to solving one of astronomy’s biggest puzzles: how cosmic giants emerged so soon after the dawn of time.
For further coverage of astrophysics and space research, visit FFRNews Astronomy, or check external sources like Universe Today and NASA for the original research and related findings.
Tags:
black holes, early universe, astronomy, space science
