Ultra - High Energy Cosmic Rays from decay of the Super Heavy Dark\n Matter Relics

In this paper we briefly discuss the problem of the origin of Ultra High\nEnergy Cosmic Rays in the framework of Top-Down models. We show that, for high\nenergy of decays and in a wide range of spectra of injected protons, their\nextragalactic flux is consistent with the observed fluxes of cosmic rays in the\nenergy range 0.1 E_{GZK}< E < 10E_{GZK}. For suitable energy and spectra of\ninjected protons, the contribution of galactic sources is moderate, in this\nenergy range, but it dominates at smaller and larger energies. In such models\nwe can expect that at these energies the anisotropy of cosmic rays distribution\nover sky will be especially small.\n Some possible manifestations of decays of super massive particles such as,\nfor example, primordial black holes with masses M_{pbh} ~ 10^{-5} g, are\nconsidered. In particular, we show that partial conversion of energy released\nduring these decays at redshifts z ~ 1000 to Ly-alpha photons can delay the\nhydrogen recombination and distort the spectrum of fluctuations of the cosmic\nmicrowave background radiation.\n

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