Detection of distant AGN by MAGIC: the transparency of the Universe to
  high-energy photons
  The recent detection of blazar 3C279 by MAGIC has confirmed previous
indications by H.E.S.S. that the Universe is more transparent to
very-high-energy gamma rays than previously thought. We show that this fact can
be reconciled with standard blazar emission models provided photon oscillations
into a veri light Axion-Like Particle occur in extragalactic magnetic fields. A
quantitative estimate of this effect explains the observed spectrum of 3C279.
Our prediction can be tested in the near future by the satellite-borne GLAST
detector as well as by the ground-based Imaging Atmospheric Cherenkov
Telescpoes H.E.S.S., MAGIC, CANGAROO III, VERITAS and by the Extensive Air
Shower arrays ARGO-YBJ and MILAGRO.
