Nature, Published online: 02 September 2020
Astronomers have detected the most powerful, most distant, and most perplexing collision of black holes yet using gravitational waves. Of the two behemoths that fused when the Universe was half its current age, at least one — weighing 85 times as much as the Sun — has a mass that was thought to be too large to be involved in such an event. And the merger produced a black hole of nearly 150 solar masses, the researchers have estimated, putting it in a range where no black holes had ever been conclusively seen before.
“Everything about this discovery is mindboggling,” says Simon Portegies Zwart, a computational astrophysicist at Leiden University in the Netherlands. In particular, he says, it confirms the existence of ‘intermediate-mass’ black holes: objects much more massive than a typical star, but not quite as big as the supermassive black holes that inhabit the centers of galaxies.
Ilya Mandel, a theoretical astrophysicist at Monash University in Melbourne, Australia, calls the finding “wonderfully unexpected”.
The event, described in two papers published on 2 September1,2, was detected on 21 May 2019, by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the United States and by the smaller Virgo observatory near Pisa, Italy. It is named GW190521 after its detection date.
