Presentation #110.06 in the session Large Scale Structure, Cosmic Distance Scale I.
The Telescope Array experiment is the largest observatory for ultrahigh energy cosmic rays in the northern hemisphere. In this talk, we report a new excess of events with E ≥ 1019.4 eV on the sky observed by the Telescope Array. Using the Li-Ma oversampling method with a 20°-radius circle, we find the excess of events in the arrival direction distribution with a local significance of about 4 standard deviations. Its center is located close to the center of the Perseus-Pisces supercluster. This supercluster is the closest supercluster within the TA’s field of view other than the local supercluster where we reside. The probability that an excess of events can occur close to the Perseus-Pisces supercluster by chance is estimated to be 3.5 standard deviations. The result indicates a cosmic ray source likely exists in the Perseus-Pisces supercluster.