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

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 20...

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Bibliographic Details
Main 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.
Format: Journal Article
Published: 2012
Online Access:http://hdl.handle.net/20.500.11937/2999
Description
Summary: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.