Studies on cosmic ray nuclei with Voyager, ACE and AMS-02: I. local interstellar spectra and solar modulation

TL;DR

This study derives local interstellar spectra of various cosmic ray nuclei using Voyager-1, ACE, and AMS-02 data, and analyzes solar modulation over two solar cycles, aiding understanding of cosmic ray propagation.

Contribution

It provides the first direct measurements of LIS spectra for multiple nuclei and models solar modulation using a non-parameterization method, improving cosmic ray propagation understanding.

Findings

LIS spectra for Helium, Lithium, Beryllium, Boron, Carbon, and Oxygen derived from combined data.

Solar modulation potential consistent with neutron monitor data.

Enhanced understanding of cosmic ray injection and propagation parameters.

Abstract

The acceleration of cosmic ray particles and their propagation in the Milky Way and the heliosphere tangle with each other, leading to complexity and degeneracy of the modeling of Galactic cosmic rays (GCRs). The recent measurements of the GCR spectra by Voyager-1 from outside of the heliosphere gave a first direct observation of GCRs in the local interstellar (LIS) environment. Together with the high-precision data near the Earth taken by ACE and AMS-02, we derive the LIS spectra of Helium, Lithium, Beryllium, Boron, Carbon, and Oxygen nuclei from a few MeV/n to TeV/n, using a non-parameterization method. These LIS spectra are helpful in further studying the injection and propagation parameters of GCRs. The nearly 20 years of data recorded by ACE are used to determine the solar modulation parameters over the solar cycles 23 and 24, based on the force-field approximation. We find general agreements of the modulation potential with the results inferred from neutron monitors and other cosmic ray data.