Energy Dependence of GCR Anisotropies in the VLISM
Abstract
As part of the SHIELD center, in this work we report on the energy dependence of galactic cosmic rays (GCRs) in the very local interstellar medium (VLISM) as measured by the Low Energy Charged Particle (LECP) instruments on the Voyager 1 and 2 spacecraft (V1 and V2). The LECP instruments include a dual-ended telescope mechanically scanning through 360° over eight equally-spaced angular sectors. The LECP telescope detects charged particles having energies from a few MeV up to GCR energies (>= ~100 MeV). As expected, LECP measurements showed a dramatic increase in GCR intensities for all sectors of the >=210 MeV LECP count rate (CH31) at the V1 heliopause crossing in 2012, however, since then the count rate data have demonstrated systematic episodes of intensity decrease for particles around 90° pitch angle. To shed light on the energy dependence of GCR anisotropies over a wide range of energies we use V1 and V2 CH31 pulse height analyzer (PHA) data, which allows us to divide the overall CH31 data into multiple smaller energy ranges, together with lower energy LECP channels. Our preliminary analysis shows that GCR anisotropies are present over a wide range of energies, and the magnitude of the anisotropies vary as a function of energies. The results of our analysis are used to place observational constraints that test existing theories or help develop new theories.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E.865N