When black holes collide: Scientists find second set of gravitational waves
For the second time, scientists have detected gravitational waves emanating from a collision between two black holes.
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"This has cemented the age of gravitational wave astronomy," said LIGO researcher Susan Scott of the Australian National University School of Physics and Engineering in Canberra. "This shows data is going to flow, that will enable us to map a lot more of the universe than we've seen before."
The collision took place 1.4 billion years ago in a small galaxy far, far away between a black hole eight times the mass of the sun and one 14 times the mass of the sun. LIGO captured the two objects orbiting each other 27 times before merging into a black hole 21 times the mass of the sun.
Because the black holes were smaller than the first detection, they spent a longer time in the detectors' sensitive band. The signal lasted 10 times longer -- about a second -- than the September collision's signal.
The signal was minute, too small to be immediately seen among the background noise. However, a supercomputer tasked with identifying gravitational wave signals found it just 70 seconds later.
The arrival time of the waves between the two detectors allows the rough position of their origin to be determined. The addition of a third, and even a fourth, detector would enable triangulation, and much more accurate measurements to the location of gravitational wave sources.
This new event "has truly put the 'O' for Observatory in LIGO," said LIGO Laboratory Deputy Director Albert Lazzarini of Caltech.
"With detections of two strong events in the four months of our first observing run, we can begin to make predictions about how often we might be hearing gravitational waves in the future. LIGO is bringing us a new way to observe some of the darkest yet most energetic events in our universe."