Voyager 2 Observations of the Anisotropy of Anomalous Cosmic Rays in the Heliosheath

Abstract

We have analyzed data collected from the Cosmic Ray Subsystem (CRS) instrument (Stone et al., 1977) on the Voyager 2 (V2) spacecraft during calibration manuevers for the magnetic field instrument while the spacecraft was located in the inner heliosheath of the heliosphere. We find that there is a diffusive anisotropy in the intensity of ∼0.5-35 MeV particles (mostly protons) that indicates that there exists a diffusive flow of these particles from the flank or tail of the heliosphere towards the nose and is slightly equatorward as well. This work supports the conclusion of an earlier, similar, but more restricted study (Stone et al., 2017) that the acceleration site of anomalous cosmic rays is back along the flank or tail of the solar wind termination shock.