A search for small and medium scale anisotropy of cosmic rays above 1 PeV registered at the Tunka-133 array

Abstract

A search for anisotropy at different scales in the arrival directions of cosmic rays with energies above 1 PeV is performed with data of the Tunka-133 array. A number of regions with angular sizes up to approximately 30 degrees that deviate from the uniform background with a statistical significance greater than three standard deviations are found using the shuffling technique both in the complete data set and its subsets in different energy ranges. Some regions with an excess of cosmic rays correlate with the distribution of possible cosmic ray sources. A comparison of the results with a similar analysis of the legacy data of the EAS MSU array is presented.