What the largest collision of black holes ever observed tells us
The unexpected recording of Ligo and Virgo reveals the existence of an intermediate category of black holes between 100 and 1000 solar masses, and opens up new theories about their birth
(image: Getty Images) International collaborations Ligo and Virgo picked up an unexpected and extraordinary signal from Space: interferometers from America to Europe recorded the gravitational waves resulting from the merger of two spiral black holes, the largest ever recorded, for a tenth of a second. The event (indicated as GW190521 and described in two articles just published in Physical Review Letters and Astrophysical Journal Letters) had been detected on May 21, 2019, but would have occurred at a time and in a place in the Universe very far from us, billions light years away and 7 billion years ago.The resulting black hole would have a mass equal to 142 times that of the Sun and would be the first of an intermediate type of black holes between 100 and 1,000 solar masses. Furthermore, it would have originated from the merger of two colossal black holes, one of 66 and one of 85 solar masses - a category of black holes deemed impossible under the laws of physics. A nice headache, in short.
