Astronomers have reported another groundbreaking discovery in space exploration: spotting for the first time two supermassive black holes in a remote galaxy, where one has been observed orbiting around the other.

Using radio telescopes, they saw what appeared to be one of the black holes orbiting around the other in gigantic, bulging galaxy about 750 million light-years away from Earth. The two are said to be one of the biggest black holes ever detected, boasting 15 billion times the mass of our sun.

Once confirmed, this would be the first pair of black holes ever seen to move relative to each other.

Breakthrough In Supermassive Black Hole Discoveries

“For a long time, we’ve been looking into space to try and find a pair of these supermassive black holes orbiting as a result of two galaxies merging. Even though we’ve theorized that this should be happening, nobody had ever seen it, until now,” reported physics and astronomy professor Greg Taylor of University of New Mexico in a statement.

The scientists have been observing the two interesting objects since 2003, imaging the radio galaxy 0402+379 using 10 radio telescopes spanning from the U.S. Virgin Islands to Hawaii as well as New Mexico to Alaska.

The galaxy was discovered back in 1995 and was confirmed in 2006 as a supermassive black hole binary system with a strange configuration.

The study’s lead author, graduate student Karishma Bansal, explained the black holes lie at a separation of around seven parsecs, the closest together that two of their kind have ever been spotted before.

Once confirmed, it will be the tiniest ever documented movement of an object in the sky, or at a recorded rate of a little over 1 micro-arcsecond a year, an angle around a billion times smaller than the smallest item the naked eye can see.

The movement clues in on how one black hole may be orbiting around the other over a 30,000-year period.

The Continuing Fuss Over Black Holes

Through new findings, the researchers hope to find further insight on the process of black holes merging, as well as how these mergers affect the evolution of galaxies surrounding them and other binary black hole systems out there.

It’s the first time that scientists have measured the orbital motion of the black hole, but this isn’t the sole supermassive black hole binary ever discovered. Galaxy 0402+379, however, is deemed a special case, as it’s argued to be a fossil cluster, as if different galaxies combined to emerge as one giant elliptical galaxy surrounded by a giant halo of X-rays.

Large galaxies are often believed to harbor huge black holes at the center. If they get together, their black holes follow suit.

The marriage of the black holes in that radio galaxy would result in a gravitational radiation burst that would be the most potent in the universe, said coauthor and Stanford professor Roger W. Romani. This convergence may never actually occur, though, given their slow orbiting and their glaring distance in light of the remaining universe age.

The findings were detailed in the Astrophysical Journal.

Earlier this year, scientists confirmed that the twin observatories of the Laser Interferometer Gravitational-wave Observatory (LIGO) detected gravitational waves for the third time.

The wave, with the detection named GW170104, came from the collision of black holes 32 and 19 times the mass of our sun, situated around 3 billion light-years away.

Last March, NASA revealed that scientists have found a supermassive black hole kicked out of the center of a distant galaxy. Scientists believed that a gravitational wave is behind the phenomenon, estimating that the energy needed to expel the black hole from the center of its galactic shelter equals 100 million supernovas simultaneously exploding.