You know how it goes: You wait forever for the unequivocal detection of gravitational waves, and then three of them come along at once. As of June of this year, one of the final proofs of Einstein’s relativistic universe has been picked up by the Laser Interferometer Gravitational-wave Observatory (LIGO) in Washington and Louisiana on three separate occasions.
In all cases, these ripples were created by catastrophic mergers of colossal black holes, with the most recently detected being the furthest away at a distance of 3 billion light-years.
Now, as reported by New Scientist, a new type of gravitational wave may have been registered by LIGO and its European counterpart, VIRGO.
A few days ago, J. Craig Wheeler – an astronomer at the University of Texas at Austin – sent out an enigmatic tweet. “New LIGO,” it reads. “Source with optical counterpart. Blow your sox off!”
The first part of that tweet strongly suggests a new gravitational wave has been detected, which would make it the fourth since the original discovery. People quickly pointed out that if this is true, then LIGO should have made the announcement with a peer-reviewed study, not an individual researcher on Twitter. Wheeler has since sent out a tweet apologizing for jumping the gun.
More importantly though, it’s the latter half of that tweet that’s sending the world of astrophysics into a spin. “Source with optical counterpart” refers to the fact that the collision that caused the gravitational waves to radiate through the universe also has a visible signature.
Black holes are notorious eaters of light, so the only remaining possibility known to science is a neutron star collision or merger.
Neutron stars are the collapsed, miniature remnants of supermassive stars, those that were originally 10-29 times the mass of our Sun. Despite ultimately having a mass of about twice that of the Sun, they are only around 10 kilometers (6.2 miles) across, which makes them some of the densest objects in the cosmos.
Strong evidence has existed for some time that neutron star collisions are possible, particularly in binary star systems that have reached the ends of their lives. Now it appears that a merger, somewhere out there, has resulted in the generation of gravitational waves – a brand new type, and a remarkable first in science.
It’s been speculated that the elliptical galaxy NGC 4993, located millions of light-years away from Earth, is the host of the neutron star merger. Optical telescopes the world over are now trained on it, hoping to find that glowing, tell-tale ember. As noted by Forbes, Hubble has already found a candidate flash.
LIGO are due to make an official announcement in the next few days. Place your bets now!