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. A., Ahlers, M., Andeen, K., Auffenberg, J., Bai, X., Baker, Mark D., Barwick, S. W., Bay, R., Bazo Alba, J. L., Beattie, K., Beatty, J. J., Bechet, S., Becker, J. K., Becker, K.-H., Benabderrahmane, M. L., Benzvi, S., Berdermann, J., Berghaus, P., Berley, D., Bernardini, E., Bertrand, D., Besson, D. Z., Bissok, M., Blaufuss, E., Boersma, D. J., Bohm, C., Böser, S., Botner, O., Bradley, L., Braun, J., Buitink, S., Carson, M., Chirkin, D., Christy, B., Clem, J., Clevermann, F., Cohen, S., Colnard, C., Cowen, D. F., d'Agostino, M. V., Danninger, M., Davis, J. C., de Clercq, C., Demirörs, L., Depaepe, O., Descamps, F.
• Other Authors: Max-Planck-Institut für Kernphysik (MPIK), Max-Planck-Gesellschaft, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: cosmic rays; neutrinos; [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE]; [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE]; [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]; [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]; Antarctic; The Antarctic; Antarc*
• Online Access: https://hal.in2p3.fr/in2p3-00706858; https://doi.org/10.1088/2041-8205/718/2/L194

We report the first observation of an anisotropy in the arrival direction of cosmic rays with energies in the multi-TeV region in the Southern 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 over 22 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 are suitable 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.