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

THE PIERRE AUGER COLLABORATION; D. MELO

The Astrophysical Journal Letters

IOP Publishing

Lugar: Bristol; Año: 2012 vol. 755 p. 1 - 7

2041-8213

The surface detector array of the Pierre Auger Observatory can detect neutrinos with energy Eu between 10**17 eV and 10**20 eV from point-like sources across the sky south of +55° and north of -65° declinations. A search has been performed for highly inclined extensive air showers produced by the interaction of neutrinos of all flavors in the atmosphere (downward-going neutrinos), and by the decay of tau leptons originating from tau neutrino interactions in 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 kps *Eu **-2 from a point-like source, 90% confidence level upper limits for kps 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 for Earth-skimming and downward-going neutrinos, respectively.