Measurement of anisotropies in cosmic ray arrival directions with the Alpha Magnetic Spectrometer on the ISS

Abstract

An analysis of anisotropies in the arrival directions of galactic protons, electrons and positrons has been performed with the Alpha Magnetic Spectrometer on the International Space Station using the first five years of data taking. Results on a dipole signal in Galactic coordinates are reported. The positron to proton and positron to electron ratio is consistent with isotropy. For energies above 16 GeV a limit of δ < 0.02 at the 95% confidence level is obtained. The electron to proton ratio is consistent with isotropy. For energies above 16 GeV a limit of δ < 0.004 at the 95% confidence level is obtained. The ratio of high rigidity protons to low rigidity protons is consistent with isotropy. For energies above 80 GV a limit of δ < 0.002 at the 95% confidence level is obtained. Limits on the absolute anisotropies in protons, electrons and positrons are consistent with the limits derived from the relative anisotropies. No indication of any time dependence is observed for all particle species within the present statistics.