In a historical event, NASA scientists have become the first to detect and confirm the existence of gravitational waves. The waves detected were discovered to have been caused by the collision and merging of two neutron stars 130 million light-years away from Earth.
“This is extremely exciting science,” said the director of NASA’s Astrophysics Division at the agency’s headquarters in Washington, Paul Hertz. “Now, for the first time, we’ve seen light and gravitational waves produced by the same event. The detection of a gravitational-wave source’s light has revealed details of the event that cannot be determined from gravitational waves alone. The multiplier effect of study with many observatories is incredible.”
What makes this discovery truly remarkable is that for decades, many in the community questioned the existence of gravitational waves. Up until this most recent discovery, scientists had relied on observing how space was affected by gravitational waves from black holes. However, due to the nature of black holes, they were never able to truly confirm the existence of the waves.
One of the only other means theorised to prove the existence of gravitational waves is observing the collision of two neutron stars. The problem with this method is that the collision and merging of two neutron stars is a once in a lifetime event. And even if such a collision was to occur the universe is vast and our ability to observe it is limited. As a result, scientists needed to know exactly where in the sky to look.
On August 17, NASA scientists got their first clue that they were onto the trail of this once in a lifetime event. At 8:41 a.m (EDT), the agency’s LIGO observatories detected a Gravity Wave “Chirp” that last about 100 seconds. The chirp was significantly longer than any ever detected and it was consistent with theoretical predictions from two merging neutron stars.
A little under two seconds after LIGO’s initial detection, NASA’s Fermi Gamma-ray Space Telescope detected a huge gamma-ray burst. Again, the burst was in line with theoretical predictions of two merging neutron stars.
Following the initial detections, NASA scientists used readings from LIGO, Fermi, Virgo, and INTEGRAL observatories to narrow the location of the two stars. 50 galaxies were identified to study more closely with optical telescopes. Amazingly, just 11 hours later, scientists observed the bright spot they were looking for in galaxy NGC 4993. The stunning grainy footage that followed revealed two neutron stars that merged 130 million years ago with the light from the event only now reaching Earth.
Image Credit: National Science Foundation/LIGO/Sonoma State University/A. Simonnet