An artist’s impression of a neutrino has interacted with a molecule of ice, producing a secondary particle—a muon—that moves at relativistic speed in the ice, leaving a trace of blue light behind it. Image caption: Nicolle R. Fuller/NSF/IceCube
With the help of an icebound detector situated a mile beneath the South Pole, an international team of scientists has found the first evidence of a source of high-energy cosmic neutrinos, ghostly subatomic particles that can travel in a straight line for billions of light-years, passing unhindered through galaxies, stars and anything else nature throws in its path.
The observation, made by the IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station, helps resolve a more than century-old riddle about what sends subatomic particles such as neutrinos and high-energy cosmic rays speeding through the universe.
Since they were first detected more than a hundred years ago, cosmic rays – highly energetic particles that continuously rain down on Earth from space – have posed an enduring mystery: What creates and propels the particles across vast distances? Where do they come from?
Two papers published on 13 July 2018 in the journal Science include the first tangible evidence that a blazar – a giant ...