June 26, 2014
Trio Of Supermassive Black Holes Discovered In Distant Galaxy
Brett Smith for redOrbit.com - Your Universe Online
While many galaxies have a supermassive black hole at their core, a new study published in the journal Nature has revealed a truly exotic phenomenon – a galaxy more than four billion light years away with three orbiting supermassive black holes at its center.
The study authors said their work indicates that there could be numerous other galaxies with two or more black holes at their center.
“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,” said study author Roger Deane from the University of Cape Town in South Africa. “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.”
In addition to being a scientific curiosity, the discovery also has implications in the hunt for gravitational waves – or the 'ripples in spacetime' predicted by Einstein’s most famous theory.
“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 spiralling into each other and merging,” said Matt Jarvis, a physicist at Oxford University. “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.”
In the discovery of these three supermassive black holes, the study team utilized a technique called Very Long Baseline Interferometry (VLBI), which involves merging the signals from large radio antennas more than 6,000 miles apart. The discovery was made using a range of European, Chinese, Russian and South African antennas, along with the 1,000-foot Arecibo Observatory in Puerto Rico.
Thus far, scientists only found a few double black holes. One explanation for their scarcity is that the black holes fuse together very quickly and readily. Another explanation, is that they orbit so closely that they're hard to detect.
“This discovery not only suggests that close-pair black hole systems emitting at radio wavelengths are much more common than previously expected, but also predicts that radio telescopes such as MeerKAT and the African VLBI Network will directly assist in the detection and understanding of the gravitational wave signal,” Jarvis said.
While the VLBI technique was essential to the new discovery, the team has also shown that the find can be picked up by much larger scale features. Black holes normally stream out large jets of material and any orbiting motion would twist these jets into a corkscrew-like shape. The study team said that these twisted jets may be a telltale sign of these unusual situations and more sensitive future telescopes like MeerKAT could be able to find binary black holes with much greater efficiency.
Image 2 (below): Illustration of how black holes in close proximity react to one another. Credit: Roger Deane, University of Cape Town