A galaxy with three supermassive black holes could help astronomers search for gravitational waves, which are the "ripples in spacetime" predicted by Einstein.
Researchers examined six systems that were believed to contain two supermassive black holes, a University of Oxford news release reported. The team ended up discovering three supermassive black holes in the region, two of which were orbiting each other like binary stars.
"What remains extraordinary to me is that these black holes, which are at the very extreme of Einstein's Theory of General Relativity, are orbiting one another at 300 times the speed of sound on Earth. Not only that, but using the combined signals from radio telescopes on four continents we are able to observe this exotic system one third of the way across the Universe. It gives me great excitement as this is just scratching the surface of a long list of discoveries that will be made possible with the Square Kilometre Array (SKA)," Doctor Roger Deane from the University of Cape Town said in the news release.
The researchers used a technique called Very Long Baseline Interferometry (VLBI) to discover the two inner black holes in the triple system. The technique combines signals from large radio antennas to see details that even the Hubble Space Telescope would miss.
"General Relativity predicts that merging black holes are sources of gravitational waves and in this work we have managed to spot three black holes packed about as tightly together as they could be before [spiraling] into each other and merging. The idea that we might be able to find more of these potential sources of gravitational waves is very encouraging as knowing where such signals should originate will help us try to detect these 'ripples' in spacetime as they warp the Universe," Professor Matt Jarvis of Oxford University's Department of Physics, an author of the paper, said in the news release.
Very little is known about these kinds of black hole systems that are to close together that they emit detectable gravitational waves. This new discovery suggests that these cluttered systems are more common than researchers previously believed.
