SEARCH FOR POINT-LIKE SOURCES OF ULTRA-HIGH ENERGY NEUTRINOS AT THE PIERRE AUGER OBSERVATORY AND IMPROVED LIMIT ON THE DIFFUSE FLUX OF TAU NEUTRINOS

PIERRE AUGER COLL. , M.T. DOVA

The Astrophysical Journal Letters

IOP

Año: 2012 vol. 755 p. 4 - 24

2041-8205

The Surface Detector array of the Pierre Auger Observatory can detect neutrinos with energy between 10^17 eV and 10^20 eV from point-like sources across the sky south of +55 deg and north of -65 deg declinations. A search has been performed for highly inclined extensive air showers produced by the interaction of neutrinos of all flavours in the atmosphere (downward-going neutrinos), and by the decay of tau leptons originating from tau neutrinos interactions in the Earth's crust (Earth-skimming neutrinos). No candidate neutrinos have been found in data up to 2010 May 31. This corresponds to an equivalent exposure of ~3.5 years of a full surface detector array for the Earth-skimming channel and ~2 years for the downward-going channel. An improved upper limit on the diffuse flux of tau neutrinos has been derived. Upper limits on the neutrino flux from point-like sources have been derived as a function of the source declination. Assuming a differential neutrino flux k_PS E^-2 from a point-like source, 90% C.L. upper limits for k_PS at the level of ~5 x 10^-7 and 2.5 x 10^-6 GeV cm^-2 s^-1 have been obtained over a broad range of declinations from the searches of Earth-skimming and downward-going neutrinos, respectively.