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Cosmic rays traced to black holes
09/11/2007 11:11 - (SA)
Washington - The sources of the most powerful rays of cosmic energy bombarding our universe likely are huge black holes at the heart of nearby galaxies, astrophysics researchers said in a report out on Thursday.
The team of scientists from 17 countries, using the Pierre Auger Observatory in Malargue, Argentina, found that active galactic nuclei are the most likely source of the highest-energy cosmic rays hitting Earth.
"We have taken a big step forward in solving the mystery of the nature and origin of the highest-energy cosmic rays, first revealed by the French physicist Pierre Auger in 1938," said the University of Chicago's James Cronin, a Nobel laureate and one of the nine authors of the report in the November 9 issue of Science.
The total 370 scientists on the team work at the facility in Argentina.
"We find the southern hemisphere sky as observed in ultra high-energy cosmic rays is non-uniform. This is a fundamental discovery," Cronin added.
"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."
"This result heralds a new window to the nearby universe and the beginning of cosmic ray astronomy," said Alan Watson of the University of Leeds.
Cosmic rays are formed by protons and atoms that travel across the universe at the speed of light. When they hit upper levels of the Earth's atmosphere they spark a shower of secondary particles that spread over more than 40 square km when they hit the ground.
Only rare top-energy cosmic rays can be linked precisely to their sources, the researchers said.
- AFP
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