Scientists with the Laser Interferometer Gravitational-wave Observatory, or LIGO, have detected the signal from a cataclysmic collision between two black holes that lie 3 billion light-years away — much farther than the previous two discoveries.
The findings, described in a paper accepted to Physical Review Letters, cement the idea that gravitational-wave astronomy — a whole new way to observe some of the most powerful events in the universe — is here to stay.
“We’re really moving from novelty to new observational science — a new astronomy of gravitational waves,” said MIT’s David Shoemaker, spokesman for the LIGO scientific collaboration.
The new signal, called GW170104, was picked up in the early morning hours of Jan. 4 by the twin L-shaped detectors in Hanford, Wash., and Livingston, La. The ripple was triggered as two black holes, spinning around slowly toward one another, finally succumbed to each other’s gravitational tug — and merged. The collision resulted in the creation of a new, single black hole.
Gravitational waves are ripples in the fabric of space-time, caused by objects accelerating or decelerating through space. Their existence was predicted more than a century ago by Albert Einstein as part of his general theory of relativity, but they were thought to be so faint as to be virtually undetectable.
LIGO changed that. Last year, the collaboration announced that its twin detectors had picked up a passing distortion in late 2015 caused by two black holes crashing into one another. A second soon followed. With the third find announced on Thursday, scientists are finally moving LIGO’s work from the examination of singular curiosities to demographic studies of the sky’s invisible denizens. And already, this third discovery is revealing that there may be some diversity in this mysterious cosmic population.
This merger between a binary pair of black holes happened around 3 billion light-years away — much farther than the first two finds (which lay around 1.3 and 1.4 billion light-years from us, respectively). The two black holes appear to have held 31.2 and 19.4 solar masses respectively, and when they coalesced the new singularity weighed in at about 49 solar masses.