Voyager 1 Galactic Cosmic-Ray Anisotropies: Electron Observations in the Very Local Interstellar Medium

Voyager 1 continues to observe time-varying enhancements and reductions in galactic cosmic-ray protons related to solar-induced transient events in the very local interstellar medium. The intensity reductions are characterized by a depletion of particles with pitch angles near 90-deg, while other directions remain generally uniform. From 2012 to 2017, Voyager 1 observed three large-scale anisotropy intervals lasting from 100 to 630 days, measured by both the Low Energy Charged Particle instrument in its > 211 MeV proton channel and by the Cosmic Ray Subsystem in its omnidirectional (>20 MeV) and bi-directional (>70 MeV) proton rates. An unexpected finding is that while protons show clear evidence of the pitch angle anisotropy in these intervals, electrons do not. If the physical mechanism responsible for the anisotropy is species-independent, equivalent or larger count rate reductions would be expected in the Cosmic Ray Subsystem's highest-energy unidirectional cosmic-ray electron rates (~18 to ~70 MeV and ~5 to ~105 MeV). However, these reductions appear negligible compared to protons, indicating that additional processes must be at work. In this study, we analyze the electron observations in detail and examine how they yield further insights into the cosmic-ray anisotropies and physical processes that govern them in the very local interstellar medium.