The collision of a pair of neutron stars, marked by ripples through the fabric of space-time and a flash brighter than a billion suns, has been witnessed for the first time in the most intensely observed astronomical event to date. The extraordinary sequence, in which the two ultra-dense stars spiralled inwards, violently collided and, in all likelihood, immediately collapsed into a black hole, was first picked up by the US-based Laser Interferometer Gravitational-Wave Observatory (Ligo).
As its twin detectors, in Louisiana and Washington state, picked up tremors in space-time that had spilled out from the merger 130m light years away, an alert went out to astronomers across the globe. Within hours, 70 space- and ground-based telescopes swivelled to observe the red-tinged afterglow, making it the first cosmic event to be “seen” in both gravitational waves and light. Dave Reitze, executive director of Ligo, said: “What is amazing about this discovery is it is the first time we’ve got a full picture of one of the most violent, cataclysmic events in the universe. This is the most intense observational campaign there has ever been.”
Einstein first predicted the existence of gravitational waves a century ago, but the first experimental proof that space itself can be stretched and squeezed took until 2015, when Ligo scientists detected a collision of black holes. But this dark merger, and the three detected since, were invisible to conventional telescopes. As the stars collided, they emitted an intense beam of gamma rays and the sky was showered with heavy elements, resolving a decades-old debate about where gold and platinum come from.
Neutron stars are the smallest, densest stars known to exist: about 12 miles wide, with a teaspoon of neutron star material having a mass of about a billion tons. The core is a soup of pure neutrons, while the crust is smooth, solid and 10 billion times stronger than steel. The 100-second hum picked up by Ligo told the story of how the two stars, each slightly heavier than the sun, approached their death. Initially separated by 200 miles, they circled each other 30 times a second. As they whirled inwards, accelerating to 2,000 orbits each second, the signal rose in pitch like a slide whistle.
MORE
The Science, Health, and Technology Room
Reply With Quote
Originally Posted by waltky
