Gravitational waves have revealed the first unevenly sized black hole pair
As far as odd couples go, this is one for the record books. The ripples in spacetime stirred up by two distant, merging black holes suggest that one of the pair was much bigger than the other. It’s the first definitively mismatched black hole pair spotted by the LIGO and Virgo collaborations, which search for the gravitational waves emitted in the cosmic encounters of black holes. The collision, detected on April 12, 2019, occurred about 2.5 billion light-years from Earth. For all previous such black hole mergers, the two partners have been of similar size. But in this case, the bigger black hole had a mass about 30 times that of the sun, while the smaller was about eight times the mass of the sun, researchers with the LIGO and Virgo collaborations reported April 18 at a meeting of the American Physical Society, which was held virtually due to the COVID-19 pandemic. Prior to this result, scientists did not know...