If this idea is true, then it could revolutionize high-energy particle research, because it implies that our galaxy is not just a place that ultra high-energy cosmic rays pass through, but could also harbor sources of these rays.

Victor Hess discovered "cosmic radiation" from the results of an unmanned balloon flight in 1912, but nearly ninety years later, scientists are still arguing about where this radiation is coming from.

Cosmic radiation, or cosmic rays, as they are more commonly called, are now known to be comprised of high-energy particles. These particles strike the upper levels of the atmosphere and create secondary particles, some of which reach the Earth's surface.

Most particles come from sources in our galaxy, the Milky Way, but those with the highest energies are thought to be coming from outside our galaxy. The common view about the sources of these extra-galactic particles is that they come from very rare "exotic sources" -- for example, the decay of dark matter -- but Sir Arnold Wolfendale of Durham University and colleagues suggest an alternative scenario.

For the first time, the researchers suggest that the highest energy particles may be produced by a more common source that is just as likely to be inside our galaxy as outside of it.

Sir Arnold and colleagues used a computer model with only one dominant type of source, be it "super" supernovae -- the explosions of massive stars -- or pulsars, collapsed rotating stars.

Their calculations showed that these sources could produce particles of the highest energies. The explanation as to why such events have not been seen in our galaxy is simply because by chance, there hasn't been a recent nearby galactic source that has gone off.

"It is important and interesting to know where the sources of these high energy particles come from because many of the atoms in our bodies and in the world around us were produced in the fiery furnaces of supernovae," said Sir Arnold.

New Journal of Physics (NJP) is a peer-reviewed, all-electronic journal publishing research in all areas of physics. It is a joint venture of the Deutsche Physikalische Gesellschaft and the Institute of Physics and available without charge on the Web.

The funding of this journal is novel in scientific publishing -- authors pay for their articles to be peer-reviewed and published. For more information on NJP, UniSci readers can contact Dr. Andrew Wray or see the website at this URL.

The Institute of Physics is a leading international professional body and learned society with over 31,000 members, which promotes the advancement and dissemination of a knowledge of and education in the science of physics, pure and applied.

[Contact: Sir Arnold Wolfendale, Dr. Alice Bows]

12-Nov-2001