Correlation function of ultrahigh-energy cosmic rays favors point sources

Abstract
We calculate the angular two-point correlation function of ultrahigh-energy cosmic rays (UHECR) observed in the AGASA and Yakutsk experiments. In both data sets, there is a strong signal at the highest energies, which is concentrated in the first bin of size equal to the angular resolution of the experiment. For the uniform distribution of sources, the probability of chance clustering is 4×10−6. Correlations are absent or insignificant at larger angles. This favors the models with compact sources of UHECR
Keywords