Super-GZK photons from photon-axion mixing

Csaba Csáki, Nemanja Kaloper, Marco Peloso, John Terning

Research output: Contribution to journalReview articlepeer-review

32 Scopus citations


We show that photons with energies above the GZK cutoff can reach us from very distant sources if they mix with light axions in extragalactic magnetic fields. The effect which enables this is the conversion of photons into axions, which are sufficiently weakly coupled to travel large distances unimpeded. These axions then convert back into high energy photons close to the Earth. We show that photon-axion mixing facilitates the survival of super-GZK photons most efficiently with a photon-axion coupling scale M ≳ 1011 GeV, which is in the same range as the scale for the photon-axion mixing explanation for the dimming of supernovae without cosmic acceleration. We discuss possible observational consequences of this effect.

Original languageEnglish (US)
Pages (from-to)57-72
Number of pages16
JournalJournal of Cosmology and Astroparticle Physics
Issue number5
StatePublished - May 2003


  • Axions
  • Cosmic rays
  • High energy photons


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