Spotters Guide Could Help Astronomers Locate Black Hole Collisions

Chuck Bednar for redOrbit.com – Your Universe Online
A team of UK astronomers has developed what they are calling a “spotters guide” to black holes that, when used in collaboration with observatories due to be activated in the US next year, could help scientists better detect the faint ripples of gravitational waves caused by black holes colliding millions of years ago.
Black holes cannot be seen, the Cardiff University researchers behind the project said, but they can be pinpointed using the Laser Interferometer Gravitational-Wave Observatory (LIGO) once activated in 2015. The new theoretical model could be used to predict all potential gravitational-wave signals which might be found by the detectors, helping astronomers gain new insight into how black holes orbit into each other and collide.
“The rapid spinning of black holes will cause the orbits to wobble, just like the last wobbles of a spinning top before it falls over,” lead investigator Dr. Mark Hannam from the Cardiff University School of Physics and Astronomy said in a statement. “These wobbles can make the black holes trace out wild paths around each other, leading to extremely complicated gravitational-wave signals. Our model aims to predict this behavior and help scientists find the signals in the detector data.”
Dr. Hannam and his Cardiff University co-authors were joined on the project by a team of postdoctoral researchers, PhD students, and collaborators from universities throughout Europe and the US. Essentially, the model they developed shows how black holes distort energy waves around them as they collide, BBC News explained on Friday, and their work could potentially help scientists detect hundreds of black holes.
This new model has already been programmed into the computer codes that LIGO scientists throughout the world will use in their hunt for black-hole mergers once the detectors become activated. Hannam and the members of his team will be working with scientists who hope to use the observatories to unravel the mysteries of the cosmos.
“Sometimes the orbits of these spinning black holes look completely tangled up, like a ball of string. But if you imagine whirling around with the black holes, then it all looks much clearer, and we can write down equations to describe what is happening,” Dr. Hannam said. “It’s like watching a kid on a high-speed spinning amusement park ride, apparently waving their hands around. From the side lines, it’s impossible to tell what they’re doing. But if you sit next to them, they might be sitting perfectly still, just giving you the thumbs up.”
However, he noted there is still much work that needs to be done.
“So far we’ve only included these precession effects while the black holes spiral towards each other. We still need to work out exactly what the spins do when the black holes collide,” the Cardiff researcher explained. “For that they need to perform large computer simulations to solve Einstein’s equations for the moments before and after the collision. They’ll need to produce many simulations to capture enough combinations of black-hole masses and spin directions to understand the overall behavior of these complicated systems.”
A paper outlining the research is published in Physical Review Letters.
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