A close correlation of filaments of galaxies with ultra-high-energy cosmic rays observed by Telescope Array experiment

Abstract

The Telescope Array (TA) experiment reported a clustering of the arrival direction distribution of ultra-high-energy cosmic rays (UHECRs) with energy above 5.7x10^19 eV. The nature of the so-called TA hotspot, however, still remains unresolved. Toward understanding the origin of the TA hotspot, we search the large-scale structure (LSS) in the local universe. We then explore the assumption that the hotspot is not related to point sources, but instead to the LSS because the cosmic magnetic field is expected to trace the LSS. We identify filamentary structures of galaxies, connected to the Virgo cluster, around the TA hotspot, and examine the statistical significance of their correlation to the hotspot. We find a close correlation of ~ 6 sigma. Our results may provide answers not only for the nature of the TA hotspot but also for the absence of UHECRs towards the Virgo cluster.