KENNEWICK — Gravitational waves from an apparent collision of two neutron stars may have been spotted for the second time in scientific history.
When two neutron stars spiral together, they undergo a violent merger that sends gravitational waves through the fabric of space and time.
The first detection of gravitational waves from the fiery collision of two neutron stars was made on Aug. 17, 2017, by the LIGO Hanford observatory near Richland and its twin observatory in Louisiana..
But the Hanford Laser Interferometer Gravitational-wave Observatory missed out on the more recent suspected sighting, which was on April 25. It was temporarily off line.
The recent detection, made only by the Livingston, La., LIGO, is important confirmation of the event two years earlier, said Jo van den Brand, spokesperson for the Virgo gravitational-wave observatory in Italy.
The likely neutron star collision in April, at a distance of 500 million light years, was too faint to be detected at Virgo.
It also did not result in any light being detected.
Black hole collisions
Two years ago not only gravitational waves from the neutron stars merger were detected, but more conventional telescopes also spotted various kinds of light, or electromagnetic radiation, including X-ray, ultraviolet, infrared and radio waves.
Black hole collisions, as first detected at LIGO Hanford in 2015 and since detected dozens of times, emit no light. But neutron stars merge into an ultradense object, emitting a fireball of gamma rays.
Neutron stars are the remnants of dying stars that undergo catastrophic explosions as they collapse at the end of their lives.
The announcement of the detection of gravitational waves in April was made on Monday at the meeting of the American Astronomical Society in Honolulu, Hawaii, after a study was submitted to “The Astrophysical Journal Letters.”
Scientists suspect that the gravitational waves detected in April were from neutron stars colliding. But questions have been raised because data shows the merged stars have about 3.4 times the mass of the Earth’s sun, which is greater than expected.
The known binary neutron star systems in our galaxy have combined masses up to only 2.9 times that of the sun.
The other possibility is that a neutron star and black hole collided, since black holes are heavier than neutron stars. But it would have to have been an exceptionally small black hole, according to scientists.