Black holes: Cosmic signal rattles Earth after 7 billion years

By Jonathan Amos
BBC Science Correspondent
2 September 2020



LIGO-VIRGO COLLABORATION
An artist's impression of the last moments before the merger of two black holes


Imagine the energy of eight Suns released in an instant.

This is the gravitational "shockwave" that spread out from the biggest merger yet observed between two black holes.

The signal from this event travelled for some seven billion years to reach Earth but was still sufficiently strong to rattle laser detectors in the US and Italy in May last year.

Researchers say the colliding black holes produced a single entity with a mass 142 times that of our Sun.

This is noteworthy. Science has long traced the presence of black holes on the sky that are quite a bit smaller or even very much larger. But this new observation inaugurates a novel class of so-called intermediate-sized black holes in the range of 100-1,000 Sun (or solar) masses.

The analysis is the latest to come out of the international LIGO-VIRGO collaboration, which operates three super-sensitive gravitational wave-detection systems in America and Europe.

More:
https://www.bbc.com/news/science-environment-53993937