Astronomers have now tallied up more gravitational wave sightings than they can count on their fingers.
Scientists with the LIGO and Virgo gravitational wave observatories report four new sets of these ripples in spacetime. Those additions bring the total count to 11, the researchers say in a study published December 3 at arXiv.org, marking major progress since the first gravitational wave detection in 2015 (SN: 3/5/16, p. 6).
All but one of the 11 sets of waves were stirred up in violent collisions of two black holes. The one remaining detection, reported in October 2017, instead came from the smashup of two stellar corpses called neutron stars (SN: 11/11/17, p. 6).
The observations are beginning to reveal how often such waves jiggle the cosmos, and the properties of the shadowy cosmic figures that unleash the ripples. For example, the data hint that black holes may have merged more frequently earlier in the universe’s history, the researchers report in a second study posted December 3 at arXiv.org. The team also concluded that few mergers involve black holes bigger than about 50 times the sun’s mass.