This time, continued observations by an array of ground-based telescopes found features indicative of chemical elements produced by the neutron capture process
"For the very first time, we see unequivocal evidence of a cosmic mine that is forging about 10,000 earth-masses of heavy elements, such as gold, platinum, and neodymium," said Mansi Kasliwal, leader of a worldwide telescope network called GROWTH taking part in the discovery.
In other words, neutron stars are the primary factories for gold in the cosmos. The results were described in a series of papers appearing in various journals such as Science and Nature.
BIG DEAL
Interestingly, the August 17 event was nearly missed because the gravitational wave signal was not immediately evident in Livingston data due to a burst of noise. However, the Hanford signal was good enough to trigger a deeper analysis of the data that quickly located the signature.
"Fermi's observation of a gamma-ray burst at nearly the same time added to the excitement and urgency of the moment," Weinstein said.
At around 10 a.m. EDT (1400 GMT), a little more than an hour after the gravitational wave was detected at the LIGO observatories, the astronomical community across the world was notified.
Originally predicted in the early 20th century by Albert Einstein, gravitational waves caused by cataclysmic cosmic events result in ripples that propagate through spacetime, just like the movement of waves away from a stone thrown into a pond.
The first three such events were detected by LIGO, and the fourth was detected simultaneously by both LIGO and Italy-based Virgo detectors.
Michael Guidry, professor of physics and astronomy at the University of Tennessee, who was not directly involved in the new discovery, called the first detection of gravitational waves produced by colliding neutron stars "quite a big deal" because the physics is "fundamentally different" from merging black holes.
"The primary difference is that for black hole mergers essentially no matter is involved, while for neutron star mergers a large amount of very dense matter is involved," Guidry told Xinhua.
"This has implications for broad issues in stellar evolution such as how the heavy elements are produced, the mechanism for gamma-ray bursts, detailed internal properties and maximum mass for neutron stars before they must collapse to black holes," he said.
"Such a detection would open entirely new avenues of inquiry in many fields of astronomy and astrophysics, so it would have a huge impact on those communities and on the future of those fields."
JUST THE BEGINNING
For example, observations of gravity from the collisions of high mass objects, like GW170817, are considered one of the few ways to test Einstein's theory.
Gregory Harry, associate professor at the American University, explained that all five gravitational wave detections agree very well with Einstein's General Theory of Relativity.
"So far we haven't gotten any new hints, and it is possible that Einstein's theory does correctly describe our universe without any changes or additions," Harry, a member of LIGO Scientific Collaboration, told Xinhua.p "But even though our detections have been very clear and strong compared to what we expected, there is still plenty of room for stronger, clearer detections that might show us what is beyond Einstein's description of gravity," he said.
The discovery of gravitational waves was so important that three U.S scientists behind it were awarded the Nobel Prize in physics this month.
"I would suggest that the Nobel Prize in physics this year wasn't given so much for the first detection of gravitational waves, but for opening up the field of gravitational astronomy," Harry said.
"Gravitational astronomy is just the beginning," he said. "We can expect many more insights into cosmology, astronomy, astrophysics, nuclear physics, gravity, and other fields from gravitational wave observations as the 21st century progresses."
