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 centres 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 Laser Interferometer Gravitational-wave Antenna (LIGO) detectors in the United States and by the smaller Virgo observatory in Italy. It is named GW190521 after its detection date.
Forbidden masses
Since 2015, LIGO and Virgo have provided new insights into the cosmos by sensing gravitational waves. These ripples in the fabric of space-time can reveal events such as the mergers of black holes that would not normally be visible with ordinary telescopes.
From the properties of the gravitational waves, such as how they change in pitch, astrophysicists can estimate the sizes and other features of the objects that produced them as they were spiralling into each other. This has revolutionized the study of black holes, providing direct evidence for dozens of these objects, ranging in mass from a few to about 50 times the mass of the Sun.
( source and full article- https://www.nature.com/articles/d41586-020-02524-w )
