In what is being described as a “transformational” moment in astronomy, scientists for the first time have verified the existence of an explosion known as a “kilonova” thanks to detectors across the globe that spotted gravitational waves triggered by a collision between the remnants of two dead stars.
The discovery announced Monday was made using the Laser Interferometer Gravitational-Wave Observatory (LIGO), which has detectors in Louisiana and Washington, along with a third detector near Pisa, Italy, known as Virgo.
At 8:41 a.m. Eastern time on Aug. 17, a gravitational wave hit the Virgo detector in Italy and, 22 milliseconds later, set off the LIGO detector in Livingston, La. Three milliseconds after that, the distortion rippled through Hanford, Wash.
LIGO detects black hole mergers as quick chirps that last a fraction of a second. This signal lasted for 100 seconds, and it vibrated at higher frequencies. From the smaller amplitude of the signal, the researchers could tell this event involved less mass than the previously observed black hole collisions.
Or described more eloquently:
The collision rattled space-time and sent a wave of fireworks across the universe, setting off sensors in space and on Earth on Aug. 17 as well as producing a long loud chirp in antennas designed to study the Einsteinian ripples in the cosmic fabric known as gravitational waves. It set off a stampede around the world as astronomers scrambled to turn their telescopes in search of a mysterious and long-sought kind of explosion called a kilonova.
Einstein first predicted a century ago that waves could ripple through space and time as black holes and other massive objects moved around. But scientists hadn’t confirmed that these gravitational waves existed until 2016, when the merger of two black holes was detected by LIGO.
Now, with the discovery of kilonovas, scientists have taken another step in verifying something that up until now had been strictly theoretical.
“It’s transformational,” said Julie McEnery, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Md., who was involved in the effort. “The era of gravitational wave astrophysics had dawned, but now it’s come of age. … We’re able to combine dramatically different ways of viewing the universe, and I think our level of understanding is going to leap forward as a result.”
Scientists say this kilonova was so bright that it could have been detected by amateur astronomers.
In the future, LIGO will alert the whole world to potential detectors, allowing citizen scientists to join professional astronomers in the global search for light from the universe’s most dramatic cataclysms.