A team of astronomers using the James Webb Space Telescope made an extraordinary discovery. They detected a massive black hole in the early universe that appears to be “napping” after eating too much food.
This black hole, about 800 million years after the Big Bang, is 400 million times the mass of our Sun. It lies dormant in its host galaxy- JADES GN+189.09144+62.22811 1001830 (hereafter GN-1001830).
An international team of astronomers led by the University of Cambridge detected this black hole. It is one of the most significant black holes ever detected by Webb during the universe’s evolution.
Remarkably, it makes up about 40% of the mass of its galaxy—far more than the typical 0.1% seen in local galaxies.
Despite its massive size, the black hole does not consume matter at its maximum rate. Its growth has slowed considerably, and it is accreting gas at only 1/100th of the expected speed.
This means that, instead of rapidly growing, the black hole is essentially in a state of cosmic dormancy. According to researchers, the most likely scenario is that black holes go through short periods of ultra-fast growth followed by long periods of dormancy. This observation challenges current models of black hole development.
Napping black holes is quite challenging to detect due to the low luminosity of the holes. However, when they accrete matter, the surrounding gas heats up and glows brightly in ultraviolet light, allowing astronomers to observe their activity. Though dormant, the black hole in question was detectable due to its enormous size and the faint glow of the gas still surrounding it.
Our Galaxy’s black hole emerged from a long period of dormancy
What’s more, its dormant state allowed the team to learn more about the host galaxy’s mass. This suggests that even small galaxies in the early universe could harbor these monstrous objects.
One of the most fascinating aspects of this discovery is that black holes might undergo short periods of hyperactive growth followed by long phases of inactivity. This behavior suggests that black holes could proliferate for a few million years before entering long dormancy periods, where they slowly accrete matter.
Standard models suggest that black holes form from the remnants of dead stars and accrete matter up to the Eddington limit, where radiation pressure counteracts the black hole’s gravitational pull. However, the enormous size of this black hole challenges these models, implying they may not fully explain how such massive black holes form and grow.
“It’s possible that black holes are born big or grow in a series of hyperactive bursts followed by extended periods of napping,” said co-author Professor Roberto Maiolino from Cambridge’s Cavendish Laboratory.
The researchers used computer simulations to determine how this giant black hole grew quickly. They think that black holes can grow fast for a short time by taking in a lot of matter, even more than usual. After that, they go through long periods where they don’t grow. The researchers believe that black holes like this might “eat” for 5 to 10 million years and then “sleep” for around 100 million years.
Co-author Professor Roberto Maiolino, from the Kavli Institute and Cambridge’s Cavendish Laboratory, said, “It sounds counterintuitive to explain a dormant black hole with periods of hyperactivity, but these short bursts allow it to grow quickly while spending most of its time napping.”
Lead author Ignas Juodžbalis from Cambridge’s Kavli Institute for Cosmology said, “Because the periods of dormancy are much longer than the periods of ultra-fast growth, it is in these periods that astronomers are most likely to detect black holes. “This was the first result I had as part of my PhD, and it took me a little while to appreciate just how remarkable it was.”
“It wasn’t until I started speaking with my colleagues on the theoretical side of astronomy that I could see the true significance of this black hole.”
Despite being challenging to detect, this black hole is almost certainly the tip of a much larger iceberg.
Maiolino said, “It’s likely that the vast majority of black holes out there are in this dormant state – I’m surprised we found this one, but I’m excited to think that there are so many more we could find.”
This groundbreaking research, was part of the JWST Advanced Deep Extragalactic Survey (JADES) and was supported by the European Research Council and the Science and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI).
As scientists continue to probe the depths of the early universe, this “sleeping giant” may soon offer more answers about the mysterious formation and growth of black holes.
Journal Reference:
- Juodžbalis, I., Maiolino, R., Baker, W.M. et al. A dormant overmassive black hole in the early Universe. Nature 636, 594–597 (2024). DOI: 10.1038/s41586-024-08210-5