BBC peers into deepest space to find the origins of a gravity “shockwave” from 7 billion years ago that was still strong enough to shake laser detectors on Earth last May – and was caused by a collision that created a single black hole 142 times as massive as our Sun:
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.
The collaboration’s laser interferometer instruments “listen” for the vibrations in space-time that are generated by truly cataclysmic cosmic events – and on 21 May, 2019, they were all triggered by a sharp signal lasting just one-tenth of a second.
Computer algorithms determined the source to be the end-stage moments of two in-spiralling black holes – one with a mass 66 times that of our Sun, and the other with 85 solar masses.
The distance to the merger was calculated to be the equivalent of 150 billion trillion km.
“It’s astounding, really,” said Prof Nelson Christensen from the Côte d’Azur Observatory in France. “This signal propagated for seven billion years. So this event happened ‘just before halftime’ for the Universe, and now it’s mechanically moved our detectors here on Earth,” he explained to BBC News.
If the science is correct on this point then the most likely explanation for the existence of an 85-solar-mass object is that it was itself the result of an even earlier black hole union.
And that, believes Prof Martin Hendry, from Glasgow University, UK, has implications for how the Universe evolved.
“We’re talking here about a hierarchy of mergers, a possible pathway to make bigger and bigger black holes,” he said. “So, who knows? This 142-solar-mass black hole may have gone on to have merged with other very massive black holes – as part of a build-up process that goes all the way to those supermassive black holes we think are at the heart of galaxies.”