Possible signature of low-scale gravity in ultrahigh-energy cosmic rays

We show that the existence of low-scale gravity at the TeV scale could lead to a direct production of photons with energy above 10²² eV due to annihilation of ultrahigh-energy neutrinos on relic massive neutrinos of the galactic halo. Air showers initialized in the terrestrial atmosphere by these ultraenergetic photons could be collected in near future by the new generation of cosmic ray experiments.