ULTRAHIGH-ENERGY COSMIC-RAYS WITHOUT GREISEN-ZATSEPIN-KUZMIN CUTOFF

We study the decays of metastable superheavy particles as the source o f ultrahigh energy cosmic rays (UHE CR). These particles are assumed t o constitute a tiny fraction xi(X) of cold dark matter in the Universe . The UHE CR fluxes produced at the decays of X particles are calculat ed. The dominant contribution is given by fluxes of photons and nucleo ns from the halo of our Galaxy and thus does not exhibit the GZK cutof f. The extragalactic components of UHE CR are suppressed by the smalle r extragalactic density of X particles and, hence, the cascade limit i s relaxed. We discuss the spectrum of produced extensive air showers a nd a signal from a Virgo cluster as signatures of this model.