Astronomers have discovered a massive black hole in the early universe that seems to be “napping” after a feast.

This black hole, found using the James Webb Space Telescope, is one of the largest ever detected in such a young part of the universe, just 800 million years after the Big Bang.

Weighing 400 million times more than our sun, this black hole is so gigantic that it makes up 40% of its galaxy’s total mass.

To put this in perspective, most black holes in today’s universe are only about 0.1% of their host galaxy’s mass.

Despite its enormous size, this black hole is currently eating very little gas—around 100 times less than its theoretical maximum limit.

This low level of activity makes it “dormant,” meaning it isn’t glowing brightly like actively feeding black holes.

Detecting such a quiet black hole is rare, but its sheer size made it possible for astronomers to spot.

This discovery challenges current models of how black holes form and grow. Typically, black holes are thought to form from collapsing stars and grow by pulling in nearby matter.

There’s a limit to how fast they can grow, called the Eddington limit, where the force of radiation pushing matter away balances the black hole’s pull. But this black hole’s size suggests something unusual is happening.

Scientists believe the answer lies in how black holes grow: short bursts of intense feeding, followed by long periods of rest.

“This black hole might have grown very quickly for 5 to 10 million years and then gone dormant for 100 million years,” explained Professor Roberto Maiolino from Cambridge University. This cycle of “hyperactivity” and “napping” may allow black holes to reach enormous sizes while spending most of their time quiet.

Dormant black holes are hard to detect because they don’t shine as brightly as active ones. Black holes are usually spotted by the glowing disk of hot gas around them when they’re actively feeding.

However, scientists say this discovery could be just the beginning. Since dormant black holes are likely common in the early universe, many more could be waiting to be found.

“This was the first result of my Ph.D., and it took some time to realize how extraordinary it was,” said lead researcher Ignas Juodžbalis. “The early universe seems to have produced some real monsters, even in tiny galaxies.”

This sleeping giant hints at many mysteries yet to uncover and suggests the early universe was home to black holes far bigger than we once imagined.

Source: University of Cambridge.