Published in Physics World, 2 Feb 2009
Evidence for axions is once again mounting as researchers claim the hypothetical particles can explain how very high-energy photons travel unimpeded through the cosmos.
Such photons and other neutral cosmic rays (aside from neutrinos) should be unable to travel inter-galactic distances because they are absorbed by the universe’s opaque background of microwaves — yet they are still detected on Earth.
Now a group led by Malcolm Fairbairn of King’s College, London, has found a correlation between where detected cosmic rays originate and where photons and axions are more likely to “mix”. The result implies that cosmic-ray photons could reach Earth from distant galaxies by temporarily converting into axions, which can bypass the microwave background without absorption. […]
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