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EnglishThe Pierre Auger Collaboration has reported evidence for anisotropy in the distribution of arrival directions of the cosmic rays with energies E > Eth = 5.5 × 1019 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 > Eth are heavy nuclei with charge Z, the proton component of the sources shouldłead to excesses in the same regions at energies E/Z. We here report thełack of anisotropies in these directions at energies above Eth/Z (for illustrative values of Z = 6,13,26). If the anisotropies above Eth 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 thełower energies. © 2011 IOP Publishing Ltd and SISSA.
| Data di pubblicazione: | 2011 |
| Titolo: | Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory |
| Autori: | |
| Citazione: | Abreu, P., Aglietta, M., Ahn, E., Albuquerque, I., Allard, D., Allekotte, I., et al. (2011). Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory. JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2011(6), 022-037. |
| Rivista: | |
| Digital Object Identifier (DOI): | http://dx.doi.org/10.1088/1475-7516/2011/06/022 |
| Abstract: | The Pierre Auger Collaboration has reported evidence for anisotropy in the distribution of arrival directions of the cosmic rays with energies E > Eth = 5.5 × 1019 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 > Eth are heavy nuclei with charge Z, the proton component of the sources shouldłead to excesses in the same regions at energies E/Z. We here report thełack of anisotropies in these directions at energies above Eth/Z (for illustrative values of Z = 6,13,26). If the anisotropies above Eth 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 thełower energies. © 2011 IOP Publishing Ltd and SISSA. |
| URL: | http://iopscience.iop.org/1475-7516/2011/06/022/pdf/1475-7516_2011_06_022.pdf |
| Appare nelle tipologie: | 1.01 Articolo in rivista |
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http://hdl.handle.net/10447/226235
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