The Virgo collaboration
Another gravitational wave has been detected, this time by the new Virgo detector in Italy. The observation comes on the tail of rumours of a possible detection of neutron stars merging, which could cause gravitational waves we can observe on Earth. But that’s not what they found.
On 14 August, the Virgo detector and the two US detectors that make up the Laser Interferometer Gravitational-Wave Observatory (LIGO) all observed the ripples in space-time caused by two black holes smashing into each other and merging.
This is the fourth gravitational wave detection ever. All four have come from pairs of black holes spiraling towards one another and then colliding, their colossal masses warping space-time as they merge. Like its forerunner, LIGO, Virgo spotted its first gravitational wave shortly after it began taking data.
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Back to black holes
The black holes that caused this latest round of gravitational waves were 31 and 25 times the mass of the sun before they merged, making this the second largest collision we’ve detected this way. They are located about 1.8 billion light years away from Earth in the direction of the constellation Eridanus in the southern sky.
“Three detectors is not just a little bit better than two; it gives us radically better information about the location of the source and what’s going on with the source,” says Kenneth Strain, a member of the LIGO collaboration at the University of Glasgow. “The numbers we can get now are much more precise than before.”
Researchers have been able to narrow down the location of this new gravitational wave, called GW170814, to an area of 60 square degrees in the sky. That’s 300 times the area of the full moon viewed from the surface of the Earth. It may still seem like a large expanse, but the addition of Virgo allows scientists to triangulate the location of a signal. In this case, they have been able to narrow the possible regions of sky that could host the source of the gravitational waves by 10 times more than with LIGO alone.
“This is just the beginning of observations with the network enabled by Virgo and LIGO working together,” said LIGO spokesperson David Shomaker. “With the next observing run planned for fall 2018 we can expect such detections weekly or even more often.”
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