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Cosmic rays go along for the Milky Way ride

The Milky Way is a barred spiral galaxy. Illustration courtesy of R. Hurt (SSC), JPL-Caltech, NASA. http://apod.gsfc.nasa.gov/apod/ap050825.html

Cosmic rays zoom through our galaxy near the speed of light. These streams of high energy particles may be accelerated in shock waves such as supernova blast waves, but theirs paths are scrambled by interstellar magnetic fields, making it difficult to determine where they came from.

A team of Japanese and Chinese researchers led by M. Amenomori analyzed data collected at the high altitude Tibet Air Shower Array, which stands 4,300 meters above sea level. They mapped tens of millions of cosmic ray events collected over 16 years.

By examining the maps, they found that cosmic rays rotate around the Milky Way with the gas and stars. The Milky Way, our galaxy, is a barred spiral galaxy with "arms" spiraling around the Sun.

The scientists also found a new cosmic ray "hotspot" close to the Cygnus spiral arm, which runs through the constellation Cygnus.

These results may lead to improved understanding of cosmic rays, supernovae, magnetic fields and galactic dynamic environments.

The research findings appear in the October 20 issue of the journal Science.