Gravitational waves form when massive objects distort spacetime surrounding them and send ripples out across the universe. Scientists caught the first-ever detection of such waves, formed by two colliding black holes, in 2015.
Since then, gravitational wave detections have only gotten stranger — and scientists have only gotten more excited. Now, a group of researchers has announced the first detection of a gravitational wave signal created by a collision involving an object larger than the largest known neutron star but smaller than the smallest known black hole.
Although the detection is too complicated for scientists to ever hope to pin down precisely what happened, the signal raises hopes for more strange observations to come. This detection could even herald a new understanding of how massive stellar explosions called supernovas happen.
Scientists caught the gravitational wave, or the “chirp,” on August 14, 2019 and were further intrigued when initial analysis suggested that the collision could have merged a black hole and a neutron star. The collision of those two objects is a type of gravitational wave event that scientists have eagerly been awaiting, since so far they have only seen mergers of matched pairs.
But as the astrophysicists ran more analyses on the data, they realised they were looking at something even stranger. This size falls into what scientists call the mass gap: an object significantly smaller than any black hole studied to date (about 5 times the mass of the sun), but also probably larger than any known neutron star (about 2.5 times the mass of the sun).
The collision occurred about 800 million light years away from Earth.