If, as the old superstition goes, bad things come in threes … how bad is it when all three things are supermassive black holes and all three of them show up at once? That’s what any living beings are dealing with in the NGC 6240 galaxy where astronomers on Earth have discovered three supermassive black holes — dead center, extremely close and spiraling ever closer until one emerges the winner in a galactic death match. If we’re close enough to see it, are we close enough to be affected by it? More importantly, are we close enough to place bets on the outcome?
“Up until now, such a concentration of three supermassive black holes had never been discovered in the universe.”
In a press release announcing the observations on the discovery published in the journal Astronomy & Astrophysics, Dr. Peter Weilbacher of the Leibniz Institute for Astrophysics Potsdam and study co-author, quickly points out what a major discovery this was. While the rare existence of two supermassive black holes in a galaxy has been found, three makes NGC 6240 unique in the universe. The reason is not surprising – galaxies may have many black holes but only one supermassive black hole in its center. Two means they are in the process of merging, which is the polite astronomy world way of saying they’re cannibalizing each other – a meal that can take a billion years — and sucking the debris into the supermassive black holes until only one remains.
“Through our observations with 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 centre.”
Professor Wolfram Kollatschny from the University of Göttingen, lead author of the study, says the “unique high-precision observations of the galaxy NGC 6240” were made using the 8 meter Very Large Telescope operated by the European Southern Observatory in Chile and its 3D MUSE spectrograph. They determined that NGC 6240 is a cosmically-close 300 million light years away and each of the supermassive black holes has a mass equivalent of more than 90 million Suns speeding towards each other at speeds of several 100 km/sec in a tight spiral that’s barely 3000 light-years across. That whoosh you hear is the sound of billions of NGC 6240 residents catching their collective breaths.
The discovery of three supermassive black holes merging into one is a unique opportunity for astronomers to observe how a supermassive galaxy is formed. Because galaxies take so long to grow in relation to the age of the universe, the merger of three – and perhaps even more – into one can explain their creation in a much shorter timeframe. As ScienceAlert explains, it may also resolve what astronomers refer to as “the final parsec problem.” In the theoretical modeling of two galaxies merging, when the supermassive black holes reach a distance of one parsec apart (about 3.2 light-years), they no longer have enough space to transfer energy and, instead of one consuming the other, they enter into a binary orbit – a close-dance to infinity. The third black hole may be the force that pulls them together into “the final parsec.”
You can place your bets now, but make sure you put the ticket in your will – the “final parsec” which will determine the winning supermassive black hole may not happen for another billion years.