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arXiv · 1109.1017

Observation of an Anisotropy in the Galactic Cosmic Ray arrival direction at 400 TeV with IceCube

IceCube Collaboration·R. Abbasi·Y. Abdou·T. Abu-Zayyad·M. Ackermann·J. Adams·J. A. Aguilar·M. Ahlers·M. M. Allen·D. Altmann·K. Andeen·J. Auffenberg·X. Bai·M. Baker·S. W. Barwick·R. Bay·J. L. Bazo Alba·K. Beattie·J. J. Beatty·S. Bechet·J. K. Becker·K. -H. Becker·M. L. Benabderrahmane·S. BenZvi·J. Berdermann·P. Berghaus·D. Berley·E. Bernardini·D. Bertrand·D. Z. Besson·D. Bindig·M. Bissok·E. Blaufuss·J. Blumenthal·D. J. Boersma·C. Bohm·D. Bose·S. Böser·O. Botner·A. M. Brown·S. Buitink·K. S. Caballero-Mora·M. Carson·D. Chirkin·B. Christy·F. Clevermann·S. Cohen·C. Colnard·D. F. Cowen·A. H. Cruz Silva·M. V. D'Agostino·M. Danninger·J. Daughhetee·J. C. Davis·C. De Clercq·T. Degner·L. Demirörs·F. Descamps·P. Desiati·G. de Vries-Uiterweerd·T. DeYoung·J. C. Díaz-Vélez·M. Dierckxsens·J. Dreyer·J. P. Dumm·M. Dunkman·J. Eisch·R. W. Ellsworth·O. Engdegård·S. Euler·P. A. Evenson·O. Fadiran·A. R. Fazely·A. Fedynitch·J. Feintzeig·T. Feusels·K. Filimonov·C. Finley·T. Fischer-Wasels·B. D. Fox·A. Franckowiak·R. Franke·T. K. Gaisser·J. Gallagher·L. Gerhardt·L. Gladstone·T. Glüsenkamp·A. Goldschmidt·J. A. Goodman·D. Góra·D. Grant·T. Griesel·A. Groß·S. Grullon·M. Gurtner·C. Ha·A. Haj Ismail·A. Hallgren·F. Halzen·K. Han
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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 May 2009 and May 2010. The data include a total of 33$\times 10^{9}$ muon events with a median angular resolution of $\sim3^{\circ}$ degrees. 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 skymap shows a different anisotropy structure including a deficit with a post-trial significance of -6.3$σ$. 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.

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IceCube Collaboration, R. Abbasi, Y. Abdou, T. Abu-Zayyad, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, M. M. Allen, D. Altmann, K. Andeen, J. Auffenberg, X. Bai, M. Baker, S. W. Barwick, R. Bay, J. L. Bazo Alba, K. Beattie, J. J. Beatty, S. Bechet, J. K. Becker, K. -H. Becker, M. L. Benabderrahmane, S. BenZvi, J. Berdermann, P. Berghaus, D. Berley, E. Bernardini, D. Bertrand, D. Z. Besson, D. Bindig, M. Bissok, E. Blaufuss, J. Blumenthal, D. J. Boersma, C. Bohm, D. Bose, S. Böser, O. Botner, A. M. Brown, S. Buitink, K. S. Caballero-Mora, M. Carson, D. Chirkin, B. Christy, F. Clevermann, S. Cohen, C. Colnard, D. F. Cowen, A. H. Cruz Silva, M. V. D'Agostino, M. Danninger, J. Daughhetee, J. C. Davis, C. De Clercq, T. Degner, L. Demirörs, F. Descamps, P. Desiati, G. de Vries-Uiterweerd, T. DeYoung, J. C. Díaz-Vélez, M. Dierckxsens, J. Dreyer, J. P. Dumm, M. Dunkman, J. Eisch, R. W. Ellsworth, O. Engdegård, S. Euler, P. A. Evenson, O. Fadiran, A. R. Fazely, A. Fedynitch, J. Feintzeig, T. Feusels, K. Filimonov, C. Finley, T. Fischer-Wasels, B. D. Fox, A. Franckowiak, R. Franke, T. K. Gaisser, J. Gallagher, L. Gerhardt, L. Gladstone, T. Glüsenkamp, A. Goldschmidt, J. A. Goodman, D. Góra, D. Grant, T. Griesel, A. Groß, S. Grullon, M. Gurtner, C. Ha, A. Haj Ismail, A. Hallgren, F. Halzen, K. Han. 2011-09-05. Observation of an Anisotropy in the Galactic Cosmic Ray arrival direction at 400 TeV with IceCube. https://doi.org/10.1088/0004-637x%2F746%2F1%2F33

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