Multipole analysis of IceCube data to search for dark matter accumulated in the Galactic halo: IceCube Collaboration

Author(s): Aartsen, MG; Ackermann, M; Adams, J; Aguilar, JA; Ahlers, M; Ahrens, M; Altmann, D; Anderson, T; Arguelles, C; Arlen, TC; Auffenberg, J; Bai, X; Barwick, SW; Baum, V; Beatty, JJ; Becker Tjus, J; Becker, KH; BenZvi, S; Berghaus, P; Berley, D; Bernardini, E; Bernhard, A; Besson, DZ; Binder, G; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, DJ; Bohm, C; Bos, F; Bose, D; Boser, S; Botner, O; Brayeur, L; Bretz, HP; Brown, AM; Casey, J; Casier, M; Chirkin, D; Christov, A; Christy, B; Clark, K; Classen, L; Clevermann, F; Coenders, S; Cowen, DF; Cruz Silva, AH; Danninger, M; Daughhetee, J; Davis, JC; Day, M; de Andre, JPAM; De Clercq, C; De Ridder, S; Desiati, P; de Vries, KD; de With, M; DeYoung, T; Diaz-Velez, JC; Dunkman, M; Eagan, R; Eberhardt, B; Eichmann, B; Eisch, J; Euler, S; Evenson, PA; Fadiran, O; Fazely, AR; Fedynitch, A; Feintzeig, J; Felde, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Franckowiak, A; Frantzen, K; Fuchs, T; Gaisser, TK; Gallagher, J; Gerhardt, L; Gier, D; Gladstone, L | Abstract: © 2015, The Author(s). Dark matter which is bound in the Galactic halo might self-annihilate and produce a flux of stable final state particles, e.g. high energy neutrinos. These neutrinos can be detected with IceCube, a cubic-kilometer sized Cherenkov detector. Given IceCube’s large field of view, a characteristic anisotropy of the additional neutrino flux is expected. In this paper we describe a multipole method to search for such a large-scale anisotropy in IceCube data. This method uses the expansion coefficients of a multipole expansion of neutrino arrival directions and incorporates signal-specific weights for each expansion coefficient. We apply the technique to a high-purity muon neutrino sample from the Northern Hemisphere. The final result is compatible with the null-hypothesis. As no signal was observed, we present limits on the self-annihilation cross-section averaged over the relative velocity distribution (Formula Presented.) down to ([Formula Presented.) for a dark matter particle mass of 700–1,000 GeV and direct annihilation into (Formula Presented.). The resulting exclusion limits come close to exclusion limits from γ-ray experiments, that focus on the outer Galactic halo, for high dark matter masses of a few TeV and hard annihilation channels.