( ADVERTISING IS NOT ALLOWED ) Telescopes Solve 100-year-old Cosmic Ray Mystery

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PostThu Nov 05, 2009 11:31 pm » by NamelessGhoul

( ADVERTISING IS NOT ALLOWED ) Telescopes Solve 100-year-old Cosmic Ray Mystery


Nearly 100 years ago, scientists detected the first signs of cosmic rays — subatomic particles (mostly protons) that zip through space at nearly the speed of light. The most energetic cosmic rays hit with the punch of a 98-mph fastball, even though they are smaller than an atom. Astronomers questioned what natural force could accelerate particles to such a speed. New evidence from the ( ADVERTISING IS NOT ALLOWED ) telescope array shows that cosmic rays likely are powered by exploding stars and stellar “winds.”

These findings were published in the Nov. 1 online issue of the journal Nature, and are being featured today in a press conference at the Fermi Science Symposium in Washington, DC. The rarest cosmic rays carry over 100 billion times as much energy as generated by any particle accelerator on Earth. (“Cosmic ray” is a historical misnomer, since they are individual particles, not a ray or beam.) Astronomers have devised ingenious methods for detecting cosmic rays that hit Earth’s atmosphere. However, detecting cosmic rays from a distance requires much more effort.

( ADVERTISING IS NOT ALLOWED ) has found new evidence for cosmic rays in the “Cigar Galaxy,” also known as Messier 82 (M82), which is located 12 million light-years from Earth in the direction of the constellation Ursa Major. “This discovery has been predicted for almost 20 years, but until now no instrument was sensitive enough to see it,” said Wystan Benbow, an astrophysicist at the Smithsonian Astrophysical Observatory. Benbow coordinated this project for the Very Energetic Radiation Imaging Telescope Array System (( ADVERTISING IS NOT ALLOWED )) collaboration.

The ( ADVERTISING IS NOT ALLOWED ) observations strongly support the long-held theory that supernovae and stellar winds from massive stars are the dominant accelerators of cosmic-ray particles. Galaxies with high levels of star formation like M82, also known as “starburst” galaxies, have large numbers of supernovae and massive stars. If the theory holds, then starburst galaxies should contain more cosmic rays than normal galaxies. The ( ADVERTISING IS NOT ALLOWED ) discovery confirms that expectation, indicating that the cosmic-ray density in M82 is approximately 500 times the average density in our Galaxy, the Milky Way.

“This discovery provides fundamental insight into the origin of cosmic rays,” said Rene Ong, a professor of physics at the University of California, Los Angeles, and the spokesperson for the ( ADVERTISING IS NOT ALLOWED ) collaboration. …

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