Search for clustering of ultra high energy cosmic rays from the Pierre Auger Observatory

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• 作者：Silvia Mollerach ; the Pierre Auger Collaboration
• 刊名：Nuclear Physics B - Proceedings Supplements
• 出版年：2009
• 出版时间：May 2009
• 年：2009
• 卷：190
• 期：Complete
• 页码：198-203
• 全文大小：280 K

文摘

We present the results of a search for clustering among the highest energy events detected by the surface detector of the Pierre Auger Observatory between 1 January 2004 and 31 August 2007. We analyse the autocorrelation function, in which the number of pairs with angular separation within an angle α is compared with the expectation from an isotropic distribution. Performing a scan in energy above 30 EeV and in angles α<30°, the most significant excess of pairs appears for E>57 EeV and for a wide range of separation angles, 9°<α<22°. An excess like this has a chance probability of 2 % to arise from an isotropic distribution and appears at the same energy threshold at which the Pierre Auger Observatory has reported a correlation of the arrival directions of cosmic rays with nearby astrophysical objects.