Most large galaxies host exactly one supermassive black hole at their center. A galaxy spotted by the James Webb Space Telescope just broke that rule in spectacular fashion, an international team has found three actively feeding supermassive black holes crammed into a single galaxy from the very early universe.
A Galaxy From the Universe’s Infancy
The galaxy, designated J0148-4214, sits more than 12.5 billion light-years from Earth. Because light takes time to travel, we’re seeing it exactly as it looked roughly 1.2 billion years after the Big Bang, when the universe was barely 9 percent of its current age. Finding one actively growing black hole in a galaxy this ancient would already be notable. Finding three is unprecedented.
Led by Dr. Hannah Übler at the Max Planck Institute for Extraterrestrial Physics, the team identified the trio through a technique called spectro-astrometry, essentially teasing apart overlapping light signatures that any earlier telescope would have blurred into a single, confusing blob. Two of the black holes sit remarkably close together at the galaxy’s center, separated by just 620 light-years. The third sits much farther out, roughly 5,500 light-years from the core.
Wildly Different Sizes, All Actively Feeding
The three black holes vary enormously in mass, roughly 80 million, 600,000, and 2 million times the mass of our Sun. Strangely, the smallest of the trio, the 600,000-solar-mass black hole, is feeding faster than its far more massive neighbor, actually exceeding the Eddington limit, the theoretical ceiling for how fast a black hole should be able to grow. The host galaxy itself weighs in at about 1.3 billion solar masses in stars, meaning these three black holes together represent a genuinely significant chunk of the galaxy’s total mass.
Solving a Puzzle That’s Bothered Astronomers for Years
Scientists have long struggled to explain how supermassive black holes managed to grow so enormous so quickly after the Big Bang. Gas accretion alone, matter simply falling in over time, doesn’t easily account for it. This discovery offers direct evidence for the other proposed pathway: galaxies colliding and merging early in cosmic history, dragging their central black holes together in the process. “It suggests that processes in the early universe were efficient at bringing massive black holes together, setting the stage for the massive black hole mergers we expect to detect with future gravitational wave observatories,” Übler said.
The two central black holes are expected to merge within the next few hundred million years, a genuine eyeblink on cosmic timescales. The distant third black hole may itself be leftover debris from an even earlier merger, possibly kicked outward by the violent gravitational recoil such a collision produces.
If you’re curious about the quieter, dormant version of a supermassive black hole sitting at the heart of our own galaxy, our profile of Sagittarius A* covers exactly how different a settled, modern black hole looks compared to this chaotic early-universe trio.
For more on the discovery, check out the full release from the Max Planck Society and the published study in Astronomy & Astrophysics.