Egg-shaped eccentric orbits form when two black holes spiral towards each other and collide under each other's strong gravitational influence.

Therefore, highly eccentric orbits may suggest black holes repeatedly snack on other black holes in densely populated areas, like the center of a galaxy.

When black holes merge, they send out gravitational waves, which differ based on the shape of the black holes' orbit, circular versus oval.

Researchers from the Rochester Institute of Technology (RIT) and the University of Florida studied GW190521 — the most massive gravitational wave signal observed from a binary black hole system — to determine if the two black holes had eccentric orbits before they merged.

"The estimated masses of the black holes are more than 70 times the size of our sun each, placing them well above the estimated maximum mass predicted currently by stellar evolution theory," Carlos Lousto, a professor at RIT and co-author on the new research, said in a statement.

"This makes an interesting case to study as a second generation binary black hole system and opens up to new possibilities of formation scenarios of black holes in dense star clusters.".

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"This represents a major advancement in our understanding of how black holes merge," Manuela Campanelli, another RIT professor and co-author, said in the statement.