Three supermassive black holes discovered at the center of one galaxy

The simultaneous merging of giant galaxies.


For the first time, scientists have captured three supermassive black holes at the center of the galaxy NGC 6240. Intriguingly these black holes are so close to each other.

The observations were made by an n international research team led by scientists from Göttingen and Potsdam using the 8-meter VLT, a telescope operated by the European Southern Observatory in Chile. The 3D MUSE spectrograph was utilized in high-resolution spatial mode together with four artificially produced laser stars and an adaptive optics system.

The pictures are obtained using sophisticated technology with a sharpness like that of the Hubble Space Telescope, yet additionally contains a spectrum for each image pixel. These spectra were decisive in deciding the movement and masses of the supermassive black holes in NGC 6240.

NGC 6240 galaxy is known as an irregular galaxy due to its particular shape. Till now, scientists used to consider that the galaxy is formed due o collision of two smaller galaxies and therefore contains two black holes in its core. These galactic ancestors moved towards each other at velocities of several 100 km/s and are still in the process of merging.

Professor Wolfram Kollatschny from the University of Göttingen said, “Through our observations with an extremely high spatial resolution we were able to show that the interacting galaxy system NGC 6240 hosts, not two – as previously assumed – but three supermassive black holes in its center.”

“Each of the three heavyweights has a mass of more than 90 million Suns. They are located in a region of space less than 3000 light-years across, i.e., in less than one-hundredth of the total size of the galaxy.”

Dr. Peter Weilbacher of the Leibniz Institute for Astrophysics Potsdam (AIP) said, “Up until now, such a concentration of three supermassive black holes had never been discovered in the universe. The present case provides evidence of a simultaneous merging process of three galaxies along with their central black holes.”

“The discovery of this triple system is of fundamental importance for understanding the evolution of galaxies over time. Until now it has not been possible to explain how the largest and most massive galaxies, which we know from our cosmic environment in the “present time,” were formed just by normal galaxy interaction and merging processes over the previous 14 billion years approximately, ie, the age of our universe.”

“If, however, simultaneous merging processes of several galaxies took place, then the largest galaxies with their central supermassive black holes were able to evolve much faster. Our observations provide the first indication of this scenario.”

Journal Reference
  1. W. Kollatschny, NGC 6240: A triple nucleus system in the advanced or final state of merging. DOI: 10.1051/0004-6361/201936540
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