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Third Time’s a Charm

LIGO detects third set of gravitational waves from colliding black holes. UF physicists have played a key role in these detections.

UF’s team of physicists working on the Advanced LIGO project are continuing their trend of cosmic discoveries. On January 4, 2017, gravitational waves were detected by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, La., and Hanford, Wash. This is the third gravitational wave event identified by the LIGO Scientific Collaboration and the Virgo collaboration. The previous detections occurred on September 14, 2015 and December 26, 2015.

The latest detection is especially exciting. Like the previous two gravitational-wave events, this one was produced by black holes that collided and merged. However, “this merger happened 3 billion years ago and it is the most distant of all confirmed events that were detected by LIGO so far,” explained University of Florida Professor of Physics Sergey Klimenko. “Like the others, within a second, it turned the energy of about two solar masses into gravitational radiation.”

The event was unambiguously identified by three independent search algorithms — one of which, Coherent WaveBurst, was developed at the University of Florida by a group of researchers led by Klimenko and fellow faculty member Professor Guenakh Mitselmakher.

The University of Florida has been an important part of the LIGO project since 1996, when UF Physics faculty began development of Coherent WaveBurst, as well as the input optics, one of the most complicated components of the LIGO detector.

Gravitational waves carry information about their origins and about the nature of gravity that cannot otherwise be obtained, and physicists have concluded that the gravitational waves, like those LIGO previously detected, were produced during the final second of the merger of two black holes — 31 and 19 times the mass of our sun — to produce a single, more massive spinning black hole that is 48 times the mass of the sun.

“Advanced LIGO continues to reward us with observations of absolutely spectacular signals from the collisions of black holes. These highly energetic events are telling us about the nature of space and time,” says David Tanner, a University of Florida professor who, together with Professor Guido Mueller, has led development and construction of the LIGO input optics.

One of the most remarkable features of all gravitational wave detections so far is that the signals arise from binary black hole systems, with masses in a range that was completely unexpected. “This is very exciting,” said UF Professor of Physics Bernand Whiting, “especially because less than two years ago, we did not know of their existence, and we are now beginning to [develop] models of their formation.”

The LIGO Laboratory is funded by the National Science Foundation and operated by Caltech and MIT, which conceived and built the Observatory. LIGO research is carried out by the LIGO Scientific Collaboration (LSC), a group of more than 1000 scientists from universities around the United States and in 14 other countries. More than 90 universities and research institutes in the LSC develop detector technology and analyze data; approximately 250 students are strong contributing members of the collaboration. The LSC detector network includes the LIGO interferometers and the GEO600 detector.