Scientists spot galaxy with 3 supermassive black holes in its core

A galaxy with three supermassive black holes swirling within it could help astronomers piece together just how some of the largest galaxies formed.

Why it matters: The discovery in the NGC 6240 galaxy located about 400 million light-years away marks the first time three supermassive black holes have been found in such close proximity to one another. The galaxy gives scientists an unprecedented chance to study the motions of three huge black holes that were once likely parts of three different galaxies as they merge.

What they found: Scientists originally thought the galaxy was host to two supermassive black holes, but new, more detailed mapping revealed the third, they report in a study in the journal Astronomy & Astrophysics.

• They think the strange galaxy formed when three different galaxies with supermassive black holes in their centers collided.
• Each black hole in the galaxy is more than 90 million times the mass of the Sun, and all are located in a space less than 3,000 light-years across.
• "We typically observe mergers of two major galaxies, which in turn harbor a black hole each, so two black holes close together happens relatively often," study author Peter Weilbacher of the Leibniz Institute for Astrophysics Potsdam told Axios via email.

What's next: After millions of years, the three black holes are expected to merge with one another, potentially creating strong gravitational waves that ripple the fabric of space and time.