Gravitational wave detectors see two different black holes as they swallowed a neutron star
Astronomers using three different gravitational wave detectors have seen the gravity ripples caused when two different black holes swallowed a nearby neutron star.
The two gravitational-wave events, dubbed GW200105 and GW200115, rippled through detectors only 10 days apart, on January 5, 2020, and January 15, 2020, respectively.
Each merger involved a fairly small black hole (less than 10 Suns in heft) paired with an object between 1½ and 2 solar masses — right in the expected range for neutron stars. Observers caught no glow from the collisions, but given that both crashes happened roughly 900 million light-years away, spotting a flash was improbable, even if one happened — and it likely didn’t: The black holes are large enough that they would have gobbled the neutron stars whole instead of ripping them into bite-size pieces.
Note the time between the detection, in early 2020, and its announcement now, in mid-2021. The data is very complex and filled with a lot of noise, requiring many months of analysis to determine if a detection was made. For example, in a third case one detector was thought to have seen another such merger but scientists remain unsure. It might simply be noise in the system. I point this out to emphasize that thought they are much more confident in these new detections, there remains some uncertainty.





