Indications of a Cosmic Ray Source in the Perseus-Pisces Supercluster

Abstract

The Telescope Array Collaboration has observed an excess of events with $E\ge 10^{19.4}\mathrm{eV}$ in the data which is centered at (RA, dec) = ($19^{\circ }$, $35^{\circ }$). This is near the center of the Perseus-Pisces supercluster (PPSC). The PPSC is about $70\mathrm{Mpc}$ distant and is the closest supercluster in the Northern Hemisphere (other than the Virgo supercluster of which we are a part). A Li-Ma oversampling analysis with $20^{\circ }$-radius circles indicates an excess in the arrival direction of events with a local significance of about 4 standard deviations. The probability of having such excess close to the PPSC by chance is estimated to be 3.5 standard deviations. This result indicates that a cosmic ray source likely exists in that supercluster.

8 pages, 4 figures, 1 table