Astronomers have discovered three actively feeding supermassive black holes inside a single distant galaxy, something never before seen so far back in the history of the universe.
The finding could help explain how enormous black holes managed to grow surprisingly quickly after the Big Bang.
The three black holes are located in a galaxy called J0148-4214, more than 12.5 billion light-years from Earth.
Because its light has taken so long to reach us, astronomers are seeing the galaxy as it existed only about 1.2 billion years after the Big Bang.
The discovery was made by an international team led by scientists at the Max Planck Institute for Extraterrestrial Physics in Germany. The study was published in Astronomy & Astrophysics.
All three black holes are actively consuming surrounding material. As gas and other matter fall toward a black hole, they form a rapidly moving disk around it. This material becomes extremely hot and produces radiation that astronomers can detect.
Two of the newly identified black holes are located near the center of the galaxy and are separated by only about 620 light-years as seen from Earth. A third lies farther out, roughly 5,500 light-years from the galactic center.
The discovery provides a remarkable snapshot of how galaxies and their black holes may have evolved in the young universe.
Scientists believe galaxies frequently collided and merged during this early period. When two galaxies came together, their central black holes could eventually move toward each other and merge as well. Repeated mergers may have helped create the enormous black holes found at the centers of many galaxies today.
To find the three black holes, the researchers used observations from the James Webb Space Telescope. Rather than seeing the black holes directly, they searched for the effects of their powerful gravity on nearby gas.
Hydrogen atoms moving at very high speeds produced distinctive signals in the galaxy’s spectrum. In the central region, those signals were too complicated to be explained by a single black hole. A special technique called spectro-astrometry allowed researchers to detect tiny differences in where the signals originated, revealing two separate central black holes. The third was identified farther from the center.
The black holes are also dramatically different in size. The largest contains about 80 million times the mass of the Sun. The other two have masses of approximately 600,000 and 2 million Suns.
Interestingly, the 600,000-solar-mass black hole is consuming material particularly rapidly, apparently exceeding a theoretical limit commonly used to describe how quickly black holes can grow.
The entire galaxy contains stars totaling about 1.3 billion times the Sun’s mass, meaning its black holes already account for a surprisingly significant amount of its mass.
Researchers expect the two central black holes could merge within the next few hundred million years. Such mergers may provide an important shortcut that allowed black holes to become enormous relatively soon after the universe began.
The third black hole is more mysterious. It could be left over from an earlier galaxy merger, could have been pushed away from the center by powerful gravitational effects, or may currently be moving inward.
The discovery suggests that multiple black holes may have played an important role in building the giant galaxies and supermassive black holes we see across the universe today.
