IceCube Neutrino Telescope Helps Rule Out Gamma Ray Bursts as Source of Cosmic Rays
Posted on April 29, 2012
The IceCube is a neutrino telescope built into a kilometer of clear Antarctic ice under the South Pole. It is seeded with an array of over 5,000 sensitive digital optical modules (DOMs) that precisely track the direction and energy of speeding muons which are created when neutrinos collide with atoms in the ice.
The IceCube Collaboration recently announced the results of an exhaustive search for high-energy neutrinos that would likely be produced if gamma-ray bursts (GRBs), violent extragalactic explosions, are the source of ultra-high-energy cosmic rays.
GRBs were predicted to be a major source of high-energy neutrinos, but IceCube did not find any, which rules out GRBs as the source of cosmic rays. This leaves active galactic nuclei (AGN), which contain supermassive black holes, as the likely source for the high-energy cosmic rays.
Nathan Whitehorn from the University of Wisconsin-Madison, who led the recent GRB research with Peter Redl of the University of Maryland, says, "This result represents a coming-of-age of neutrino astronomy. IceCube, while still under construction, was able to rule out 15 years of predictions and has begun to challenge one of only two major possibilities for the origin of the highest-energy cosmic rays, namely gamma-ray bursts and active galactic nuclei."
The research was published here in the journal, Nature.
The IceCube Neutrino Observatory's 5,160 digital optical modules are suspended from 86 strings reaching a mile and a half below the surface at the South Pole. Each sphere contains a photomultiplier tube and electronics to capture the faint flashes of muons speeding through the ice, their direction and energy -- and thus that of the neutrinos that created them. Here is a video (kade before it was built) that explains the purpose of the IceCube Neutrino Observatory. Take a look: