Scientists observing a distant galaxy are currently trying to find an explanation as to why some black holes are not surrounded by stars.

One theory that they came up with is that this may have been caused by two or more galaxies colliding into one another, Discovery News reported.

The scientists came up with this concept while peering at the galaxy dubbed as SDSS J1126+2944 using the Hubble Space Telescope and NASA's Chandra X-ray Observatory. During their observations, they came across two neighboring massive black holes.

However, they were surprised to see that the first black hole had starts surrounding it while the other one was naked, or star-less. Given the relatively close distance between the two, their different appearances left the scientists puzzled.

"One black hole us starved of stars, and has 500 times fewer stars associated with it than the other black hole," Julie Cameford of the University of Colorado and lead researcher of the study said in a press statement.

"The question is why there's such a discrepancy," she added.

The scientists believe that these two may have originally belonged to different galaxies. But, through a cosmic collision, the two galaxies merged together into one, which is now known as SDSS J1126+2944.

Usually, in this kind of phenomenon, the black holes two, which are generally located in the center of the galaxies, will become one as well. But in the case of SDSS J1126+2944, it seems the two massive black holes are still in the process of merging into one supermassive black hole.

As for the naked nature of one of the black holes, the scientists noted that during collisions, the tidal and gravitational forces produced by the merger causes the surrounding stars to scatter. But eventually, they will settle into their respective positions once the galaxy stabilizes. This could suggest that the stars around the naked black hole have not yet settled into place yet.

Another theory suggest that this black hole is actually an intermediate mass black hole. According to the scientists, black holes such as this are formed when a number of smaller black holes collide with each other to form one really big black hole. However, the scientists noted that further studies are needed in order to prove this concept.

"Theory predicts that intermediate black holes should exist, but they are difficult to pinpoint because we don't know exactly where to look," researcher Scott Barrows explained. "This unusual galaxy may provide a rare glimpse of one of these intermediate mass black holes."