The Abundance of Low Energy Cosmic Ray Boron and Nitrogen Nuclei Measured at Voyager 1 Beyond the Heliopause, Where Do They All Come From? An Interpretation Using a Leaky Box Galactic Propagation Model

TL;DR

Voyager 1 measurements of low energy cosmic ray boron and nitrogen nuclei reveal their origins and propagation characteristics, with models suggesting a source component near the sources and confirming low nitrogen abundance relative to solar levels.

Contribution

This study provides a detailed interpretation of Voyager 1 data using a nested leaky box model, highlighting the source contributions and low nitrogen abundance in cosmic rays.

Findings

Voyager 1 data below 40 MeV/nuc fits a source component near the sources.

Nitrogen source ratio N/O is approximately 6.3%, lower than solar abundance.

The model confirms a low nitrogen abundance in cosmic ray sources.

Abstract

Uncertainties in the Voyager data itself as well as the cross sections for production of these secondaries at these low energies are an important limitation on the estimates of the amount of matter traversed. We also attempt a fit to the B observations at low energies by considering a source component of B generated in 1.0 g/cm2 of matter near the sources but after acceleration. This would be equivalent to a Nested LBM. In this model the V1 data below 40 MeV/nuc is now well fit. For Nitrogen, which is dominated by a source component at these low energies, a fit to the data between 10-130 MeV/nuc can be obtained with a N/O source ratio = 6.3 + 1.0% and a path length compatible with the H and He propagation as noted above. This Voyager observation confirms earlier measurements of a low N abundance in the cosmic ray source relative to what is found for solar abundances, for example, where the N/O ratio is found to be ~12%.