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Observation of an Anisotropy in the Galactic Cosmic Ray Arrival Direction at 400 TeV with IceCubeIn 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 x 10(exp 9) muon events with a median angular resolution of approx. 3 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 sigma. 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.
Document ID
20120007458
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Abbasi, R.
(Wisconsin Univ. Madison, WI, United States)
Abdou, Y.
(Ghent Univ. Belgium)
Abu-Zayyad, T.
(Wisconsin Univ. United States)
Ackermann, M.
(Deutsches Elektronen-Synchrotron Zeuthen, Germany)
Adams, J.
(Canterbury Univ. Christchurch, New Zealand)
Aguilar, J. A.
(Wisconsin Univ. Madison, WI, United States)
Ahlers, M.
(Oxford Univ. Oxford, United Kingdom)
Allen, M. M.
(Pennsylvania State Univ. University Park, PA, United States)
Altmann, D.
(Rheinisch Westfalische Technische Hochschule Aachen Aachen, Germany)
Andeen, K.
(Rutgers Univ. Piscataway, NJ, United States)
Auffenberg, J.
(Wuppertal Univ. Germany)
Bai, X.
(South Dakota School of Mines and Technology Rapid City, SD, United States)
Baker, M.
(Wisconsin Univ. Madison, WI, United States)
Barwick, S. W.
(California Univ. Irvine, CA, United States)
Bay, R.
(California Univ. Berkeley, CA, United States)
Bazo Alba, J. L.
(Deutsches Elektronen-Synchrotron Zeuthen, Germany)
Beattie, K.
(California Univ., Lawrence Berkeley National Lab. Berkeley, CA, United States)
Beatty, J. J.
(Ohio State Univ. Columbus, OH, United States)
Bechet, S.
(Brussels Univ. Belgium)
Becker, J. K.
(Ruhr Univ. Bochum, Germany)
Becker, K. H.
(Wuppertal Univ. Germany)
Benabderrahmane, M. L.
(Deutsches Elektronen-Synchrotron Zeuthen, Germany)
BenZvi, S.
(Wisconsin Univ. Madison, WI, United States)
Berdermann, J.
(Deutsches Elektronen-Synchrotron Zeuthen, Germany)
Stamatikos, M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 25, 2013
Publication Date
January 23, 2012
Publication Information
Publication: The Astrophysical Journal
Volume: 746
Issue: 1
Subject Category
Astronomy
Report/Patent Number
GSFC.ABS..5857.2012
Distribution Limits
Public
Copyright
Other

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