Ultrahigh-Energy Neutrino Interactions and Neutrino Telescope Event Rates

We present results for neutrino-nucleon cross sections for energies up to 10$^21$eV, of relevance to the detection of ultrahigh energy galactic and extragalactic neutrinos. At the highest energies, our results are about 2.4 times larger than previous estimates. Using these new cross sections, we predict neutrino telescope event rates for the upward moving muons initiated by the neutrino interactions in the Earth and for contained-vertex events in the PeV range due to neutrino-electron interactions. We show that future neutrino detectors, such as AMANDA, BAIKAL, DUMAND and NESTOR have a very good chance of detecting neutrinos which originate in the Active Galactic Nuclei.