Search for Nuclei Sources in the Ultra-High Energy Cosmic Ray Data

Abstract

We present a new method to search for heavy nuclei sources, on top of background, in the Ultra-High Energy Cosmic Ray data. We apply it to the 69 events with energies E>55 EeV published by the Pierre Auger Collaboration. We find a set of events for which the method reconstructs the source near the Virgo galaxy cluster. The probability to have a comparable set of events in some background is ~ 0.7 %. The reconstructed source is located at ~ 8.5 degrees from the active galaxy M87. The probability to reconstruct the source at less than 10 degrees from M87 for data already containing a comparable set of events is ~ 0.4 %. This may be a hint at the Virgo galaxy cluster as an ultra-high energy heavy nuclei source. We discuss the capability of current and near future experiments to test this possibility. Such a scenario gives a self-consistent description of the Auger anisotropy and composition data at the highest energies.