Three supermassive black holes closely orbiting around each other have been discovered in a galaxy more than 4 billion light years away from Earth.
This is the tightest trio of black holes known to date and is remarkable since most galaxies have just one at their center (usually with a mass between 1 million to 10 billion times that of the Sun).
The discovery suggests that these closely packed supermassive black holes are far more common than previously thought. The team, led by South African Dr Roger Deane from the University of Cape Town, used a technique called Very Long Baseline Interferometry (VLBI) to discover the inner two black holes of the triple system. This technique combines the signals from large radio antennas separated by up to 10 000 kilometers to see detail 50 times finer than that possible with the Hubble Space Telescope. The observations were done with the European VLBI Network (EVN) and the data were correlated at the Joint Institute for VLBI in Europe (JIVE) in Dwingeloo, the Netherlands.
The study has been published online in the journal Nature.