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Observation of anisotropy in the galactic cosmic-ray arrival directions at 400 TeV with IceCube

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Authors
Abbasi, R.
Abdou, Y.
Abu-Zayyad, T.
Ackermann, M.
Adams, J.
Aguilar, J.
Ahlers, M.
Allen, M.
Altmann, D.
Andeen, K.
Auffenberg, J.
Bai, X.
Baker, M.
Barwick, S.
Bay, R.
Bazo Alba, J.
Beattie, K.
Beatty, J.
Bechet, S.
Becker, J.
Becker, K.
Benabderrahmane, M.
BenZvi, S.
Berdermann, J.
Berghaus, P.
Berley, D.
Bernardini, E.
Bertrand, D.
Besson, D.
Bindig, D.
Bissok, M.
Blaufuss, E.
Blumenthal, J.
Boersma, D.
Bohm, C.
Bose, D.
Böser, S.
Botner, O.
Brown, A.
Buitink, S.
Caballero-Mora, K.
Carson, Michael
Chirkin, D.
Christy, B.
Clevermann, F.
Cohen, S.
Colnard, C.
Cowen, D.
Cruz Silva, A.
D'Agostino, M.
Danninger, M.
Daughhetee, J.
Davis, J.
De Clercq, C.
Degner, T.
Demirörs, L.
Descamps, F.
Desiati, P.
De Vries-Uiterweerd, G.
DeYoung, T.
Díaz-Vélez, J.
Dierckxsens, M.
Dreyer, J.
Dumm, J.
Dunkman, M.
Eisch, J.
Ellsworth, R.
Engdegård, O.
Euler, S.
Evenson, P.
Fadiran, O.
Fazely, A.
Fedynitch, A.
Feintzeig, J.
Feusels, T.
Filimonov, K.
Finley, C.
Fischer-Wasels, T.
Fox, B.
Franckowiak, A.
Franke, R.
Gaisser, T.
Gallagher, J.
Gerhardt, L.
Gladstone, L.
Glüsenkamp, T.
Goldschmidt, A.
Goodman, J.
Góra, D.
Grant, D.
Griesel, T.
Groß, A.
Grullon, S.
Gurtner, M.
Date
2012
Type
Journal Article

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Citation
Abbasi, R. and Abdou, Y. and Abu-Zayyad, T. and Ackermann, M. and Adams, J. and Aguilar, J. and Ahlers, M. et al. 2012. Observation of anisotropy in the galactic cosmic-ray arrival directions at 400 TeV with IceCube. Astrophysical Journal. 746 (1).
Source Title
Astrophysical Journal
DOI
ISSN
School
Department of Exploration Geophysics
URI
Collection
Abstract

In this paper we report the first observation in the Southern hemisphere of an energy dependence in the Galactic cosmic-ray anisotropy up to a few hundred TeV. This measurement was performed using cosmic-ray-induced muons recorded by the partially deployed IceCube observatory between 2009 May and 2010 May. The data include a total of 33 × 109 muon events with a median angular resolution of ~3°. A sky map of the relative intensity in arrival direction over the Southern celestial sky is presented for cosmic-ray median energies of 20 and 400 TeV. The same large-scale anisotropy observed at median energies around 20 TeV is not present at 400 TeV. Instead, the high-energy sky map shows a different anisotropy structure including a deficit with a post-trial significance of –6.3σ. This anisotropy reveals a new feature of the Galactic cosmic-ray distribution, which must be incorporated into theories of the origin and propagation of cosmic rays.