Evidence of Intermediate-Scale Energy Spectrum Anisotropy of Cosmic Rays E$\geq$10$^{19.2}$ eV with the Telescope Array Surface Detector

An intermediate-scale energy spectrum anisotropy has been found in the arrival directions of ultra-high energy cosmic rays of energies above $10^{19.2}$ eV in the northern hemisphere, using 7 years of Telescope Array surface detector data. A relative energy distribution test is done comparing events inside oversampled spherical caps of equal exposure, to those outside, using the Poisson likelihood ratio. The center of maximum significance is at $9^h16^m$, 45$\Deg$, and has a deficit of events with energies $10^{19.2}$$\leq$E$<$$10^{19.75}$ eV and an excess for E$\geq$10$^{19.75}$ eV. The post-trial probability of this energy anisotropy, appearing by chance anywhere on an isotropic sky, is found by Monte Carlo simulation to be 9$\times$10$^{-5}$ (3.74$\sigma_{global}$).