Small-scale anisotropy in the cosmic ray flux observed by GRAPES-3 at TeV energies

Abstract

Cosmic ray (CR) anisotropy of several scales have been observed over the last decade by a number of experiments located in the Northern and Southern hemispheres. The GRAPES-3 experiment, located at 11.4◦ N can observe a significant portion of both the hemispheres and covers about 56% of the sky at TeV energies. Several small-scale anisotropic features, with a strength of ∼ 10−4 − 10−3, have been observed using four years of GRAPES-3 data collected within a period of 2013-2016, by using the method of time-scrambling. Two striking hot-spot regions have been observed with a significance of more than 4σ. These structures are consistent with the observations reported by Milagro, ARGO-YBJ and HAWC. These structures, their characteristic features and a comparison of results from other experiments are described in this work. © Copyright owned by the author(s) under the terms of the Creative Commons.