Astronomers have found three actively feeding supermassive black holes inside a single galaxy more than 12.5 billion light-years from Earth, offering what researchers call a rare glimpse of how giant black holes grew and interacted when the universe was in its infancy.
The galaxy, known as J0148-4214, appears to astronomers as it existed just 1.2 billion years after the Big Bang. "This is the first evidence of three active black holes in a single galaxy in the distant Universe," said Hannah Übler, a research group leader at the Max Planck Institute for Extraterrestrial Physics and lead author of the study, published in a peer-reviewed astronomy journal.
Two neighbors, and an outlier
Two of the black holes sit near the galaxy's center, separated by a projected distance of just 620 light-years, while the third lies much farther out, roughly 5,500 light-years away. Their masses vary dramatically — approximately 80 million, 600,000 and 2 million times that of the sun — and, surprisingly, the smallest of the three central pair is growing fastest, feeding at a rate that exceeds the theoretical limit most models place on black hole growth.
Researchers identified the trio by analyzing distinctive patterns in light from hydrogen gas swirling near each black hole, using the James Webb Space Telescope's Near Infrared Spectrograph in a mode that lets astronomers map how light varies across different parts of a galaxy. Without that spatial detail, the team says, they likely would have detected only one of the three black holes.
A preview of mergers to come
The two black holes near the galaxy's center are expected to merge within the next few hundred million years, a process scientists believe was common as galaxies collided and combined in the early universe. "These results are extremely exciting," said Roberto Maiolino, a co-author and professor at the University of Cambridge. "They suggest that black hole merging may be an additional, fast route for their rapid growth in the early Universe." The more distant third black hole, researchers say, could be a remnant kicked outward by an earlier, uneven merger, or one still slowly drifting toward the galaxy's core.
The team estimates the galaxy's total stellar mass at about 1.3 billion suns, with the three black holes representing a significant share of that total — a finding researchers say suggests other distant galaxies likely harbor similar hidden, multiple black hole systems still waiting to be found.