In case you haven’t heard about LIGO(Laser Interferometer Gravitational Waves Observatory), you’ve been missing out on a lot. LIGO is a gravitational wave observatory. It is blind to visible light and the rest of the electromagnetic spectrum, all it cares about, is detecting gravitational waves, which, unlike light, is not a part of the electromagnetic spectrum. The LIGO is made up of twin sites in Louisiana and Washington.
The LIGO made the headlines when the facilities observed two neutron stars combine, the only one of its kind yet recorded. This scientific revolution comes not-so-late after the first gravitational waves were detected. Astronomers have been trying to detect the space-time ripples for the whole of the last century, ever since Albert Einstein predicted them through his equations of general relativity(1916). Einstein stated that objects in the Universe warp the fabric of space-time around them and when they move, they create disturbances in this fabric, a bit like a stone leaving ripples when thrown in a pond. But detecting these disturbances as waves is not an easy task.
The ripples from nearby planets and stars are too weak to pick up, that’s why astronomers have been looking for the biggest waves they can find, ones coming from the most massive objects with large masses moving at extremely high speeds – merging black holes and neutron stars. Until now, all of the detections made by the LIGO have been from mergers of black holes. These discoveries told scientists a great deal about the black holes found in the Universe, but they don’t offer much opportunity for further observations because black holes have intense gravitational pulls, due to which not even light can escape from them.
Even if astronomers could point out where a black hole merger occurred, telescopes that view the universe in electromagnetic spectrum wouldn’t be able to see anything. That’s why astronomers have been eager to find merging neutron stars and finally they’ve got the chance they had been eagerly waiting for, just after the establishment of the new gravitational waves observatory, Virgo in Italy. Having three detectors pick up the waves makes it much easier to find the sources of these signals in the sky.
By timing when the waves reach each detector, astronomers can triangulate the location of the wave source in space. As soon as the LIGO team suspected they had caught a new wave, text alerts were sent to astronomers around the world, telling them to get ready for a hunt. Based on the LIGO measurements, the two neutron stars combined 130 million light-years away, much closer than the black hole mergers which occurred billions of light-years beyond Earth.
And each neutron star was between 1.1 and 1.6 times the mass of our Sun, though they were probably just about 10 miles across.
Their resulting impact is known as a kilonova, an incredibly explosive event. The merger creates a gargantuan fireball, and the superdense materials from the two stars shoot outward in all directions. Initial light measurements from the kilonova show just how fast that material was moving, too: the outer layers of the kilonova sped away from the event at speeds close to one-third the speed of light, according to astronomers’ estimates. These events aren’t just explosive either; they’re also thought to be factories for the production of the heaviest elements in the Universe. And the light emitted from the kilonova showed how those elements, such as gold, were produced in the wake of the merger. Being called as one of the greatest discoveries of the decade, this event surely marks the beginning of a new era of universal understanding.