Colorado University Boulder researchers have identified the mechanism that is responsible for the presence of asymmetric stellar clusters surrounding supermassive black holes in several galaxies. It has been found that the stars orbiting the black hole are forcibly attracted into it and are eventually destroyed at a rate of one per year.
The paper published in the Astrophysical Journal gives the reason for the eccentric behavior of the stellar orbits near certain supermassive black holes. It was found that each star which follows an elliptical orbit around the supermassive black hole will eventually overlap or interact with each other to disrupt their orbits. This gravitational disruption will bring the stars closer to the black hole which gradually pulls them inside.
Several galaxies including Andromeda have been found with asymmetric stellar clusters in the form of a disc. These disc-shaped asymmetric disks are formed even during the merger of two gas-rich galaxies, said scientists.
Ann Marie Madigan, Associate JILA Fellow who led the study said, "This force builds up in these stellar orbits and changes their shapes. Eventually, a star reaches its nearest approach to the black hole and it gets shredded. We predict that in a post-galactic merger period, a supermassive black hole will swallow one star per year." This is around 10,000 times more than other rate predictions.
The research findings prove the reason for the higher mortality rate of stars in galaxies having supermassive black holes at its center. It also suggests that eccentric nuclear discs would be more common around central black holes in galaxies.
However, more research needs to be done for better understanding of galactic merger and evolution of the Universe.
Madigan stated: "Andromeda is likely past the peak of this process, having undergone a merger long ago. But with higher resolution data, we may be able to find younger eccentric disks in more distant galactic nuclei."