@Article{PierreAugerCollaborationAbreu+Pastor2011,
author="Pierre Auger Collaboration (Abreu, P. et al
and Pastor, S.",
title="Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory",
journal="Journal of Cosmology and Astroparticle Physics",
year="2011",
publisher="Iop Publishing Ltd",
volume="06",
number="6",
pages="022--17pp",
optkeywords="ultra high energy cosmic rays; cosmic ray experiments",
abstract="The Pierre Auger Collaboration has reported. evidence for anisotropy in the distribution of arrival directions of the cosmic rays with energies E > E-th = 5.5 x 10(19) eV. These show a correlation with the distribution of nearby extragalactic objects, including an apparent excess around the direction of Centaurus A. If the particles responsible for these excesses at E > E-th are heavy nuclei with charge Z, the proton component of the sources should lead to excesses in the same regions at energies E/Z. We here report the lack of anisotropies in these directions at energies above E-th/Z (for illustrative values of Z = 6, 13, 26). If the anisotropies above E-th are due to nuclei with charge Z, and under reasonable assumptions about the acceleration process, these observations imply stringent constraints on the allowed proton fraction at the lower energies.",
optnote="ISI:000292332400022",
optnote="exported from refbase (https://references.ific.uv.es/refbase/show.php?record=676), last updated on Fri, 15 Jul 2011 12:53:12 +0000",
issn="1475-7516",
doi="10.1088/1475-7516/2011/06/022",
opturl="http://arxiv.org/abs/1106.3048",
opturl="https://doi.org/10.1088/1475-7516/2011/06/022",
archivePrefix="arXiv",
eprint="1106.3048",
language="English"
}