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AnonTechie [soylentnews.org] writes:

Today, physicists and astronomers around the world are announcing a whole new kind of gravitational wave signal at a National Science Foundation press conference in Washington, DC. But it’s not just gravitational waves. That August day, x-ray telescopes, visible light, radio telescopes, and gamma-ray telescopes all spotted a flash, one consistent with a pair of neutron stars swirling together, colliding and coalescing into a black hole. The observation, called a “kilonova,” simultaneously answered questions like “where did the heavy metal in our Universe come from” and “what causes some of the gamma-ray bursts scientists have observed since the 60s.” It also posed new ones.

The Fermi Gamma-ray Space telescope [nasa.gov] started the dominos at 8:41 am EDT, detecting what NASA astrophysicist Julie McEnery called a “perfectly normal short gamma-ray burst,” a quick flash of invisible light from some distant source. Scientists have known about short and long gamma-ray bursts for a long time, surmising that the short ones must come from colliding neutron stars, but weren’t sure. McEnery then received an email with a subject line in all caps—the bursts had a friend. Two seconds earlier, one of the two Laser Interferometer Gravitational Wave Observatories (LIGO) [caltech.edu], the one in Washington State had set off an alert from receiving a gravitational wave signal (folks received the alert after the Fermi announcement). Analysis later revealed that the other LIGO detector in Louisiana also heard the signal but glitched and didn’t report it.

This wave would be perfectly explained by a collision 130 million light years away between two neutron stars, dead stars so dense that a spoonful would weigh something like the combined weight of all of the humans on Earth. Each star probably had a mass between one and two times that of the Sun, resulting in a black hole a little less than three times the mass of the Sun. They named the event GW170817. The collision would have sent a bright beam of radiation outward in an explosion, called a kilonova, and gravitational waves towards the Earth. The third gravitational wave detector currently sensitive to astronomical sources, Virgo in Italy, did not hear the waves since they were in the detector’s blind spot. This helped the researchers better determine the stars’ location in the sky.

[...] All in all, the discovery marks an important milestone in gravitational wave astronomy and proof that LIGO and Virgo do more than spot colliding black holes. At present, the detectors are all receiving sensitivity upgrades. When they come back online, they may see other sources like some supernovae or maybe even a chorus of background gravitational waves from the most distant stellar collisions.

https://gizmodo.com/observatories-across-the-world-announce-groundbreaking-1819500578 [gizmodo.com]

[Also Covered By]:

In a First, Gravitational Waves Linked to Neutron Star Crash [nationalgeographic.com]

New gravitational wave discovery confirms dawn of a new field of astronomy [sheffield.ac.uk]

What Have Gravitational-Wave Detectors Discovered? [space.com]

Original Submission