Observations of high energy neutrinos with waterice neutrino telescopes.pdf

a r X i v : a s t r o - p h / 0 6 0 2 0 2 5 v 1 1 F e b 2 0 0 6 Observations of high energy neutrinos with water/ice neutrino telescopes. Albrecht Karle Department of Physics, University of Wisconsin, Madison, U.S.A. E-mail: karle@ Abstract. The search for high energy neutrinos of astrophysical origin is being conducted today with two water/ice Cherenkov experiments. New instruments of higher performance are now in construction and more are in the RD phase. No sources have been found to date. Upper limits on neutrino fluxes are approaching model predictions. Results are reported on the search for point sources, diffuse fluxes, gamma ray bursts, dark matter and other sources. 1. Introduction High energy neutrino astronomy will offer a new view of the Universe. The observation of the highest energy cosmic rays and the detection of galactic and extragalactic sources of gamma rays are proof that very energetic sources of non-thermal radiation exist. The detection of sources of high energy neutrinos will provide insights into the origin of the highest energy radiation. Neutrinos have been detected from the Sun and from Supernova 1987a; both observations representing fundamental breakthroughs in astrophysics and physics. Neutrino telescopes now in operation and construction aim at higher energies. This report will focus on the energy range aimed for by under water/ice neutrino telescopes: ≈ 1011 eV to ≈ 1018eV. At the same time an increasing effort is underway to detect neutrinos at the highest energies to beyond 1020 eV. Markov and Zheleznikh [1] suggested the detection of neutrinos in water via the process νl(ν?l) + N → l ± + X of upward or horizontal neutrinos interacting with a nucleon N of the matter surrounding the detector. A significant fraction of the neutrino energy will be carried away by the produced lepton. For the important case of the muon the angle between the parent neutrino and the muon is less than 1? at 1 TeV energy and it becomes very small at hi