Photograph by : Aurore Simonnet/NASA
"This is a fundamental discovery," said Nobel laureate James Cronin, the University Professor Emeritus in Physics at the University of Chicago. "The age of cosmic-ray astronomy has arrived. In the next few years, our data will permit us to identify the exact sources of these cosmic rays and how they accelerate these particles."
British-led scientists now believe the fast-moving particles that bombard the atmosphere are blasted across space from massive black holes at the centre of active galaxies.
Cosmic rays, discovered in 1912, are fast-moving subatomic particles that include the nuclei of hydrogen, oxygen, carbon, nitrogen and iron atoms. Evidence suggests they may increase the risk of cancer in pilots and air crews on long-haul flights.
Medium-energy cosmic rays are known to come from exploding stars, while the Sun and other stars emit lower energy cosmic rays. But the source of ultra-high energy rays, which are 100 million times more energetic than anything produced by the most powerful atom smashers, has remained unexplained.
Suggested sources have included giant black holes, noisy radio galaxies, shock waves from colliding galaxies, echoes of the "Big Bang", and bizarre theoretical objects called "cosmic strings".
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