Salvatore Vitale describes how gravitational-wave signals suggest black holes completely devoured their companion neutron stars.

Recently, an international team of scientists, including researchers at MIT, announced the detection of a new kind of astrophysical system: a collision between a black hole and a neutron star — two of the densest, most exotic objects in the universe.

Scientists have detected signals of colliding black holes, and colliding neutron stars, but had not confirmed a merging of a black hole with a neutron star until now. In a study appearing today in The Astrophysical Journal Letters, the scientists report observing not just one, but two such rare events, each of which gave off gravitational waves that reverberated across a large swath of the universe before reaching Earth in January 2020, just 10 days apart.