On Jan. 5, 2020, astrophysicists heard a chirp from a distant part of the cosmos, some 900 million light-years away. The fleeting sound was unlike any they’d heard before and was caused by a great ripple in space-time — a gravitational wave — that spread out across the universe from over 900 million light-years away, washing over the Earth and pinging detectors. Chirp.
Then, 10 days later, they heard another, similar sound. A cosmic twin. Gravitational waves had once again pinged Earth’s detectors. Chirp.
After careful analysis, the two signals have been identified as emanating from extreme, never-before-seen events in deep space: the collision between a black hole and a neutron star.
The pair of collisions (or, less poetically, “mergers”) are detailed in a new study published in the Astrophysical Journal Letters on Tuesday, featuring over 1,000 scientists from the LIGO/Virgo and KAGRA collaborations, a multinational effort to hunt for gravitational waves. The two newly described events are named GW200105 and GW200115, for the dates they were discovered, and provide the first definitive evidence of an elusive merger.
www.cnet.com/news/astronomers-detect-black-holes-swallowing-up-neutron-stars-for-the-first-time/