A team scientists have discovered a trio of supermassive black holes, closely orbiting the center of a distant galaxy over four billion light years away from Earth.

The scientists found the three black holes while examining six galaxies. The black holes are reportedly the "tightest trio of black holes" ever discovered at such a great distance, with two of the black holes orbiting each other like binary stars.

The discovery should help astronomers in their quest to look for gravitational waves.

"What remains extraordinary to me is that these black holes, which are at the very extreme of Einstein's Theory of General Relativity, are orbiting one another at 300 times the speed of sound on Earth," Roger Deane from the University of Cape Town and the study's lead author said, in a statement, according to a University of Oxford press release.

Their research was published in the journal Nature recently.

Closely-packed supermassive black holes are more common in the universe than previously believed.

The researchers believe that gravitational waves originate among merging black holes and the current study of the black hole trio will is expected to provide insight into this concept.

"The idea that we might be able to find more of these potential sources of gravitational waves is very encouraging as knowing where such signals should originate will help us try to detect these 'ripples' in spacetime as they warp the Universe," Matt Jarvis, a professor at Oxford University and the study's co-author, said in the statement.

Scientists used a technique called Very Long Baseline Interferometry, or VLBI, to discover the inner two black holes in the system, according to the study.

The discovery was made by using the European VLBI Network, which includes European, Chinese, Russian and South African antennas, according to the release.

Very little is known about the orbiting black holes emitting detectable gravitational waves, but scientists believe that future radio telescopes will help astronomers better understand how black holes shape galaxies.

"This exciting discovery perfectly illustrates the power of the VLBI technique, whose exquisite sharpness of view allows us to see deep into the hearts of distant galaxies," Keith Grainge of the University of Manchester said, in the statement.

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