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SEARCHES FOR EXTENDED AND POINT-LIKE NEUTRINO SOURCES WITH FOUR YEARS OF ICECUBE DATA
Aartsen, M. G.,Ackermann, M.,Adams, J.,Aguilar, J. A.,Ahlers, M.,Ahrens, M.,Altmann, D.,Anderson, T.,Arguelles, C.,Arlen, T. C.,Auffenberg, J.,Bai, X.,Barwick, S. W.,Baum, V.,Beatty, J. J.,Tjus, J. Be IOP Publishing 2014 The Astrophysical journal Vol.796 No.2
<P>We present results on searches for point-like sources of neutrinos using four years of IceCube data, including the first year of data from the completed 86 string detector. The total livetime of the combined data set is 1373 days. For an E-2 spectrum, the observed 90% C. L. flux upper limits are similar to 10(-12) TeV-1 cm(-2) s(-1) for energies between 1 TeV and 1 PeV in the northern sky and similar to 10(-11) TeV-1 cm(-2) s(-1) for energies between 100 TeV and 100 PeV in the southern sky. This represents a 40% improvement compared to previous publications, resulting from both the additional year of data and the introduction of improved reconstructions. In addition, we present the first results from an all-sky search for extended sources of neutrinos. We update the results of searches for neutrino emission from stacked catalogs of sources and test five new catalogs; two of Galactic supernova remnants and three of active galactic nuclei. In all cases, the data are compatible with the background-only hypothesis, and upper limits on the flux of muon neutrinos are reported for the sources considered.</P>
Observation of the cosmic-ray shadow of the Moon with IceCube
Aartsen, M. G.,Abbasi, R.,Abdou, Y.,Ackermann, M.,Adams, J.,Aguilar, J. A.,Ahlers, M.,Altmann, D.,Auffenberg, J.,Bai, X.,Baker, M.,Barwick, S. W.,Baum, V.,Bay, R.,Beatty, J. J.,Bechet, S.,Becker Tjus, American Physical Society 2014 PHYSICAL REVIEW D - Vol.89 No.10
The IceProd framework: Distributed data processing for the IceCube neutrino observatory
Aartsen, M.G.,Abbasi, R.,Ackermann, M.,Adams, J.,Aguilar, J.A.,Ahlers, M.,Altmann, D.,Arguelles, C.,Auffenberg, J.,Bai, X.,Baker, M.,Barwick, S.W.,Baum, V.,Bay, R.,Beatty, J.J.,Becker Tjus, J.,Becker, Elsevier 2015 Journal of parallel and distributed computing Vol.75 No.-
<P><B>Abstract</B></P> <P>IceCube is a one-gigaton instrument located at the geographic South Pole, designed to detect cosmic neutrinos, identify the particle nature of dark matter, and study high-energy neutrinos themselves. Simulation of the IceCube detector and processing of data require a significant amount of computational resources. This paper presents the first detailed description of IceProd, a lightweight distributed management system designed to meet these requirements. It is driven by a central database in order to manage mass production of simulations and analysis of data produced by the IceCube detector. IceProd runs as a separate layer on top of other middleware and can take advantage of a variety of computing resources, including grids and batch systems such as CREAM, HTCondor, and PBS. This is accomplished by a set of dedicated daemons that process job submission in a coordinated fashion through the use of middleware plugins that serve to abstract the details of job submission and job management from the framework.</P> <P><B>Highlights</B></P> <P> <UL> <LI> IceProd is a lightweight distributed workflow management framework. </LI> <LI> Uses existing middleware and protocols. </LI> <LI> Runs at user-level and is easily adaptable to other applications. </LI> <LI> It has been successful in managing 450k cores across 25 computing centers. </LI> <LI> Identified areas of improvement including scalability and load balancing. </LI> </UL> </P>
Searches for small-scale anisotropies from neutrino point sources with three years of IceCube data
Aartsen, M.G.,Ackermann, M.,Adams, J.,Aguilar, J.A.,Ahlers, M.,Ahrens, M.,Altmann, D.,Anderson, T.,Arguelles, C.,Arlen, T.C.,Auffenberg, J.,Bai, X.,Barwick, S.W.,Baum, V.,Beatty, J.J.,Becker Tjus, J. North-Holland 2015 Astroparticle physics Vol.66 No.-
<P><B>Abstract</B></P> <P>Recently, IceCube found evidence for a diffuse signal of astrophysical neutrinos in an energy range of ∼ 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 <SUP> E - 2 </SUP> energy spectrum ranges from ∼ 1.5 · <SUP> 10 - 8 </SUP> GeV/cm<SUP>2</SUP> s<SUP>−1</SUP>, in the case of one assumed source, to ∼ 4 · <SUP> 10 - 10 </SUP> GeV/cm<SUP>2</SUP> s<SUP>−1</SUP>, in the case of 3500 assumed sources.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We applied two methods to search for clusters of astrophysical neutrinos on background. </LI> <LI> Investigated both hemispheres separately and three different energy spectra. </LI> <LI> Saw underfluctuation consistent with background and set limits on astrophysical flux. </LI> <LI> Compared limits to recently found astrophysical flux to constrain number of sources. </LI> <LI> Excluded few sources of very hard energy spectra for seen astrophysical flux. </LI> </UL> </P>