Are Black Holes Slowly Taking Over Star Cluster Palomar 5 Orbiting Milky Way Galaxy?

Scientists have discovered a massive collection of more than 100 black holes in the Milky Way Galaxy.

The black holes are located in the center of a star cluster that is more than 80,000 light-years away from Earth. There is almost three times the number of black holes that physicists would expect to find.

The stars themselves will be ejected over the next billion years, leaving only the black holes left.

The discovery aids our understanding of Palomar 5, a puzzling star cluster, and how it may evolve in the future.

However, it may also aid in our understanding of the destiny of other similar clusters in our galaxy.

It could also help explain the bizarre phenomenon of thin streams of stars seen recently in our galaxy that do not appear to be tied to a cluster.

"Palomar 5 with its stream is truly unique, and is a sort of Rosetta Stone for understanding stream formation," study author Mark Gieles, an astrophysicist at the Catalan Institution for Research and Advanced Studies at the University of Barcelona, told Vice in an email.

Following the discovery of gravity waves, Gieles and the team investigated what occurs when a star cluster contains black holes. Gieles said the team recognized that Palomar 5's high escape rate and big radius might both be the outcome of a massive population of black holes.

"Combined with the above, I decided that we should try to model Palomar 5 and its stream and see if all peculiar properties can be explained with black holes," he added.

Oversized Black Hole Populations in Star Cluster Palomar 5

Researchers said large clusters of black holes, such as Palomar 5 could have given rise to the mysterious streams.

Palomar 5 is located in the "Galactic Halo," a ring of ancient stars that surrounds the Milky Way. It is one of the most sparse clusters in the halo.

It is also noted for its two long "tails," which are made up of ejected star streams. These tails stretch throughout the night sky, allowing scientists to utilize them to learn more about how they form throughout the universe.

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Scientists modeled the lifespan of the cluster's stars individually in the latest study. Researchers cannot check for black holes since, as their name implies, they are impossible to see, so the new study depends on the way to figure out how many there are.

"It is believed that a large fraction of binary black hole mergers form in star clusters," Fabio Antonini, a co-author on the study from Cardiff University, said per Science Daily.

"A big unknown in this scenario is how many black holes there are in clusters, which is difficult to work out because we cannot see black holes. Our new method gives us a way to learn how many black holes there are in a star cluster by simply looking at the stars they eject."

They demonstrated that those two distinguishing characteristics — its sparse structure and tails — may be the product of 100 black holes accounting for 20% of its mass.

Black Holes are Slowly Taking Over Palomar 5

Because there are so many black holes, and they are all so enormous, the stars will perish faster than the black holes. As a result, the cluster inflated, and its tail grew in the simulation.

Eventually, the black holes' gravitational pull will be so strong within the cluster that all of the stars will be ejected out, leaving only the black holes.

Experts have now provided an emotive explanation: black holes are slowly but steadily engulfing Palomar 5, a process that is rapidly displacing stars.

According to the scientists, that could be the same story as the other streams of stars, which formerly occupied clusters before being ejected by the lingering black holes. According to the experts, they do not appear to be affiliated with a cluster because their original one experienced the same fate as Palomar 5.

Researchers reported their findings in a paper titled "A supra-massive population of stellar-mass black holes in the globular cluster Palomar 5" published in Nature Astronomy.