Astronomers detect colliding neutron stars for the first time

Combination of gravitational waves and light used for first time to make historic observation

An international research collaboration, including four Northwestern University astronomers, is the first to detect the spectacular collision of two neutron stars using both gravitational waves and light.

The discovery ushers in an exciting new era in astronomy — multi-messenger astronomy with gravitational waves — less than two years after the first detection of gravitational waves opened a new window onto the universe.

Northwestern’s Vicky Kalogera, the leading astrophysicist in the LIGO Scientific Collaboration (LSC), was one of six experts on a special panel at the National Science Foundation press conference announcing the news at the National Press Club in Washington, D.C.

Gravitational waves were directly detected for the first time Sept. 14, 2015, by the Laser Interferometer Gravitational-Wave Observatory (LIGO), confirming Einstein’s theory of general relativity. Following the discovery, the observatory’s architects were awarded the 2017 Nobel Prize in Physics.

The historic discovery of colliding neutron stars — which happened the morning of Aug. 17 with the longest gravitational-wave signal detected to date and a short gamma ray burst signal — was made by thousands of scientists and engineers using the U.S.-based LIGO; the Europe-based Virgo gravitational wave detector; and some 70 ground- and space-based observatories, including NASA’s Hubble Space Telescope.

The neutron stars’ spiral death dance in a nearby galaxy, 130 million light-years from Earth, ended with an extremely violent and bright collision — powerful enough to forge gold, platinum, lead and other heavy elements.

“Mergers of double neutron stars were predicted over many decades to drive such powerful explosions, but this multi-messenger discovery brings two key pieces of the puzzle together for the first time,” Kalogera said. “Our discovery confirms a lot of our theoretical predictions, including that double neutron stars give rise to gamma rays, optical, infrared, X-rays and radio waves. At the same time, there are hints in these observations that are providing new mysteries we still need to understand.”


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