Journal
ASTROPARTICLE PHYSICS
Volume 66, Issue -, Pages 39-52Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.astropartphys.2015.01.001
Keywords
Extraterrestrial neutrinos; Astrophysical neutrinos; Point sources; IceCube; 2pt-correlation; Multipole analysis
Funding
- US National Science Foundation-Office of Polar Programs
- US National Science Foundation-Physics Division
- University of Wisconsin Alumni Research Foundation
- Grid Laboratory Of Wisconsin (GLOW) grid infrastructure at the University of Wisconsin - Madison
- Open Science Grid (OSG) grid infrastructure
- US Department of Energy
- National Energy Research Scientific Computing Center
- Louisiana Optical Network Initiative (LONI) grid computing resources
- Natural Sciences and Engineering Research Council of Canada
- WestGrid and Compute/Calcul Canada
- Swedish Research Council
- Swedish Polar Research Secretariat
- Swedish National Infrastructure for Computing (SNIC)
- Knut and Alice Wallenberg Foundation, Sweden
- German Ministry for Education and Research (BMBF)
- Deutsche Forschungsgemeinschaft (DFG)
- Helmholtz Alliance for Astroparticle Physics (HAP)
- Research Department of Plasmas with Complex Interactions (Bochum), Germany
- Fund for Scientific Research (FNRS-FWO), FWO Odysseus programme, Flanders Institute
- Belgian Federal Science Policy Office (Belspo)
- University of Oxford, United Kingdom
- Marsden Fund, New Zealand
- Australian Research Council
- Japan Society for Promotion of Science (JSPS)
- Swiss National Science Foundation (SNSF), Switzerland
- National Research Foundation of Korea (NRF)
- Danish National Research Foundation, Denmark (DNRF)
- Science and Technology Facilities Council [ST/J000507/1, ST/L000474/1, PP/C506205/1] Funding Source: researchfish
- STFC [ST/L000474/1, PP/C506205/1, ST/J000507/1] Funding Source: UKRI
- Direct For Mathematical & Physical Scien [1307472] Funding Source: National Science Foundation
- Division Of Physics [1307472] Funding Source: National Science Foundation
- Division Of Physics
- Direct For Mathematical & Physical Scien [1205403] Funding Source: National Science Foundation
- Division Of Physics
- Direct For Mathematical & Physical Scien [1403586] Funding Source: National Science Foundation
Ask authors/readers for more resources
Recently, IceCube found evidence for a diffuse signal of astrophysical neutrinos in an energy range of similar to 60 TeV to the PeV-scale [1]. The origin of those events, being a key to understanding the origin of cosmic rays, is still an unsolved question. So far, analyses have not succeeded to resolve the diffuse signal into point-like sources. Searches including a maximum-likelihood-ratio test, based on the reconstructed directions and energies of the detected down- and up-going neutrino candidates, were also performed on IceCube data leading to the exclusion of bright point sources. In this paper, we present two methods to search for faint neutrino point sources in three years of IceCube data, taken between 2008 and 2011. The first method is an autocorrelation test, applied separately to the northern and southern sky. The second method is a multipole analysis, which expands the measured data in the northern hemisphere into spherical harmonics and uses the resulting expansion coefficients to separate signal from background. With both methods, the results are consistent with the background expectation with a slightly more sparse spatial distribution, corresponding to an underfluctuation. Depending on the assumed number of sources, the resulting upper limit on the flux per source in the northern hemisphere for an E-2 energy spectrum ranges from similar to 1.5. 10(-8) GeV/cm(2) s(-1), in the case of one assumed source, to similar to 4. 10(-10) GeV/cm(2) s(-1), in the case of 3500 assumed sources. (C) 2015 Elsevier B.V. All rights reserved.
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