Search for Astrophysical Sources of Neutrinos Using Cascade Events in IceCube
- Department of Physics, University of Adelaide, Adelaide, 5005 (Australia)
- DESY, D-15735 Zeuthen (Germany)
- Dept. of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch (New Zealand)
- Université Libre de Bruxelles, Science Faculty CP230, B-1050 Brussels (Belgium)
- Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark)
- Oskar Klein Centre and Dept. of Physics, Stockholm University, SE-10691 Stockholm (Sweden)
- Département de physique nucléaire et corpusculaire, Université de Genève, CH-1211 Genève (Switzerland)
- Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen (Germany)
- Department of Physics, Marquette University, Milwaukee, WI, 53201 (United States)
- Dept. of Physics, Pennsylvania State University, University Park, PA 16802 (United States)
- Dept. of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
- III. Physikalisches Institut, RWTH Aachen University, D-52056 Aachen (Germany)
- Physics Department, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States)
- Dept. of Physics and Astronomy, University of California, Irvine, CA 92697 (United States)
- Institute of Physics, University of Mainz, Staudinger Weg 7, D-55099 Mainz (Germany)
The IceCube neutrino observatory has established the existence of a flux of high-energy astrophysical neutrinos, which is inconsistent with the expectation from atmospheric backgrounds at a significance greater than 5 σ . This flux has been observed in analyses of both track events from muon neutrino interactions and cascade events from interactions of all neutrino flavors. Searches for astrophysical neutrino sources have focused on track events due to the significantly better angular resolution of track reconstructions. To date, no such sources have been confirmed. Here we present the first search for astrophysical neutrino sources using cascades interacting in IceCube with deposited energies as small as 1 TeV. No significant clustering was observed in a selection of 263 cascades collected from 2010 May to 2012 May. We show that compared to the classic approach using tracks, this statistically independent search offers improved sensitivity to sources in the southern sky, especially if the emission is spatially extended or follows a soft energy spectrum. This enhancement is due to the low background from atmospheric neutrinos forming cascade events and the additional veto of atmospheric neutrinos at declinations ≲−30°.
- OSTI ID:
- 22679860
- Journal Information:
- Astrophysical Journal, Vol. 846, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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