Four new kinds of gravitational waves detected from crashing black holes
It’s the largest batch of detections released at once and includes an event that is both the most massive and the most distant collision observed to date
Scientists have identified four more signals of massive collisions in outer space, including the largest to date, bringing the total ofgravitational wave detection s to 11 in just a few years.
A team of researchers affiliated with the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US and its European counterpart Virgo unveiled the four new detections on Saturday 1 December at a scientific meeting.
“It took science a century to confirm Einstein's prediction of the existence of gravitational waves,” Sheila Rowan, a physicist at the University of Glasgow, says. “The pace of our discoveries since then has been exhilarating, and we're anticipating many more exciting detections to come.”
Gravitational waves are often described as ripples in space-time and are produced by pairs of black holes or neutron stars – two forms of extremely massive, dense remnants created when a star explodes. Pairs of these objects orbit each other, drawing ever closer to one another and causing gravitational waves to ripple outward as they do so until they eventually collide.
Thanks to the LIGO and Virgo detectors scientists on Earth can now capture these signals, which lets them study the collisions and objects involved. As the field of gravitational-wave science has matured, new detections have taken on a different tone. The first detection, which was announced in February of 2016, was remarkable for its very existence, but in the nearly three intervening years binary black hole mergers have begun to verge on the routine.
The new announcement is the largest batch of detections released at once, and it includes an event that is both the most massive and the most distant collision observed to date. And now that scientists have a total of ten binary black hole merger detections under their belts, as well as one binary neutron star merger, announced last autumn, they can start to draw some conclusions about black holes in general.
"Gravitational waves give us unprecedented insight into the population and properties of black holes," Chris Pankow, an astrophysicist at Northwestern University, Illinois, says – for example, that most black holes formed by stars encompass less than 45 Suns’ of material. "We now have a sharper picture of both how frequently stellar mass binary black holes merge and what their masses are. These measurements will further enable us to understand how the most massive stars of our universe are born, live and die."
“Gravitational waves give us insight into the population and properties of black holes”