MEASUREMENT OF THE ANISOTROPY OF COSMIC-RAY ARRIVAL DIRECTIONS WITH ICECUBE

• Published in: The Astrophysical Journal
• Main Authors: Abbasi, R, Abdou, Y, Abu-Zayyad, T, Adams, J, Aguilar, J, Ahlers, M, Andeen, K, Auffenberg, J, Bai, X, Baker, M, Barwick, S, Bay, R, 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
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Antarctic; The Antarctic; Antarc*
• Online Access: https://doi.org/10.1088/2041-8205/718/2/L194; https://ora.ox.ac.uk/objects/uuid:b1e02fc0-ef4a-4c72-a811-1eeabb09732f

We report the first observation of an anisotropy in the arrival direction of cosmic rays with energies in the multi-TeV region in theSouthern sky using data from the IceCube detector. Between 2007 June and 2008 March, the partially deployed IceCube detector was operated in a configuration with 1320 digital optical sensors distributed over22 strings at depths between 1450 and 2450 m inside the Antarctic ice. IceCube is a neutrino detector, but the data are dominated by a large background of cosmic-ray muons. Therefore, the background data aresuitable for high-statistics studies of cosmic rays in the southern sky. The data include 4.3 billion muons produced by downward-going cosmic-ray interactions in the atmosphere; these events were reconstructed with a median angular resolution of 3° and a median energy of ∼20 TeV. Their arrival direction distribution exhibits an anisotropy in right ascension with a first-harmonic amplitude of (6.4±0.2 stat.±0.8 syst.) × 10-4. © 2010 The American Astronomical Society.