This is an artist’s impression of merging neutron stars. University of Warwick/Mark Garlick
For the first time in history, scientists have observed and measured a gravitational wave event in multiple mediums including optical, gamma ray and X-ray.
An international group of researchers observed on August 17 the source of a gravitational wave that was created by the merger of a pair of neutron stars formed a kilonova that ejected heavy elements into space including gold.
Using the NASA/ESA Hubble Space Telescope, the researchers captured images of the galaxy in visible and infrared light, witnessing a new bright object within NGC 4993 that was brighter than a nova but fainter than a supernova.
“It was surprising just how closely the behavior of the kilonova matched the predictions,” Nial Tanvir, a professor at the University of Leicester and leader of another Hubble observing team, said in a statement. “It looked nothing like known supernovae, which this object could have been and so confidence was soon very high that this was the real deal.”
The researchers estimated that about 130 million years ago a pair of heavy and dense neutron stars spiraled around each other, bringing each other closer to one another and making them spin faster until they were circling more than 100 times per second.
A collision ensued, sending a shockwave through the fabric of spacetime, traveling across the universe at the speed of light until it rippled through Earth on Aug. 17.
On. Oct. 16, the U.S.-based Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo detector in Italy announced that all three of their detectors had picked up the gravitational waves from the event and two seconds later a satellite looking for gamma rays registered a burst from the same direction of the sky.
The newly married neutron stars gave off a bright flash of light visible for days afterwards, allowing the world’s most advanced telescopes to point in that direction of the sky.
The scientists believe this could lead to new discoveries, including determining the precise location of the galaxy where the event happened, which previous LIGO detection has not been able to do. They also confirmed that gravitational waves travel at approximately the speed of light and they calculated the rate at which the universe is expanding using gravitational waves.
“Any one of these findings would be groundbreaking on its own merits, and here we got all the pieces together in the span of 12 hours,” Daniel Holz, an associate professor of physics and astrophysics who led the University of Chicago team, which was involved in both the LIGO and Dark Energy Survey discoveries, said in a statement.
“This is akin to seeing the lightning bolt and hearing the thunder. We have just witnessed the birth of a new field of astronomy,” he added. “It’s been an unbelievable few weeks.”
Researchers from the University of Warwick have also confirmed the presence of gold origin in the universe after the gravitational waves, producing as much gold as the mass of the Earth.
“The exquisite observations obtained in a few days showed we were observing a kilonova, an object whose light is powered by extreme nuclear reactions,” Joe Lyman, Ph.D., who was observing at the European Southern Observatory at the time, said in a statement. “This tells us that the heavy elements, like the gold or platinum in jewelry are the cinders, forged in the billion degree remnants of a merging neutron star.”
