Hard component of ultra-high energy cosmic rays and vortons

Observed events of ultra-high energy cosmic rays may indicate a hard component for the energy spectrum of their flux, which might have origin in the decay of long-lived vortons presumably condensed in the galactic halo. To be consistent with the needed present density, vortons may have been formed during the breaking of an abelian symmetry contained in a large GUT group like E-6 and a part of them could haven survived the destabilization caused by the electroweak transition. (C) 2002 Elsevier Science B.V. All rights reserved.