An international research team, including physicists from the Weizmann Institute of Science, has for the first time succeeded in observing a merger of two colliding neutron stars. The merger was simultaneously picked up by three detectors built for this purpose: the two belonging to the Laser Interferometer Gravitational-Wave Observatory, or LIGO, in the United States, and the Virgo detector in Italy. The observation may help determine how such heavy elements as uranium, iodine and gold were formed and enhance our understanding of some of the most violent events in the history of the universe.
An international research team, including physicists from the Weizmann Institute of Science, has for the first time succeeded in observing a merger of two colliding neutron stars. The merger was simultaneously picked up by three detectors built for this purpose: the two belonging to the Laser Interferometer Gravitational-Wave Observatory, or LIGO, in the United States, and the Virgo detector in Italy. The observation may help determine how such heavy elements as uranium, iodine and gold were formed and enhance our understanding of some of the most violent events in the history of the universe.
The merger was observed on August 17 and announced to the public on October 16. Analysis of the observations is being published in a number of leading scientific journals, including The Astrophysical Journal, Nature,and Science.
Two years ago, in September 2015, the LIGO detectors had already produced a sensational first: They had enabled scientists to observe gravitational waves for the very first time. Those waves, predicted by Albert Einstein a hundred years earlier, had come from a collision between two massive black holes and had taken 1.3 billion years to reach Earth. In the wake of the finding, the 2017 Nobel Prize in Physics was announced earlier this month “for decisive contributions to the LIGO detector and the observation of gravitational waves."
The newly detected collision and merger of two neutron stars had occurred relatively “recently”: Radiation from the merger had taken “only” about 100 million years to arrive on Earth. But most important, it has provided scientists with more information than the black hole collision. “When black holes collide, the only thing we can detect is gravitational waves, everything else is swallowed inside,” says Prof. Avishay Gal-Yam of Weizmann’s Particle Physics and Astrophysics Department. “But neutron stars are relatively lighter than black holes, so when they collide and merge, a small part of their mass and radiation does escape and can be detected along with gravitational waves.”
Read more at Weizmann Institute of Science
Image: This artist's impression shows two tiny but very dense neutron stars at the point at which they merge and explode as a kilonova. (Credit: ESO/L. Calçada/M. Kornmesser)
