14–24 Jul 2025
CICG - International Conference Centre - Geneva, Switzerland
Europe/Zurich timezone
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Voyager 1 Observations of Galactic Cosmic Ray Isotopes in the Very Local Interstellar Medium: Evidence for Primary 2H and B

16 Jul 2025, 15:35
15m
Room B

Room B

Talk Cosmic-Ray Direct & Acceleration CRD

Speaker

Igor Moskalenko

Description

We present the first measurements of the energy spectra of the isotopes of galactic cosmic rays (GCRs) with nuclear charge $Z=1-14$ in the very local interstellar medium (VLISM). We also update our previously published energy spectra of GCR elements in the VLISM from $Z=1-28$ (Cummings et al. 2016) for the new longer time period of observations, 1/1/2013 through 12/31/2021. The observations are from the Cosmic Ray Subsystem (CRS) (Stone et al. 1977) on the Voyager 1 (V1) spacecraft and cover the $Z$-dependent energy range from $\sim$$3-661$ MeV/nucleon. The data are fit to eight models using the GCR propagation code GALPROP, and provide a new set of GCR elemental source abundances. The models all have injection spectra as power laws in rigidity, all with the same power-law index, and fit exclusively to the V1 data. The eight models differ in the relative abundances and by having two options for production cross sections and four options for total fragmentation cross sections. The VLISM energy spectra generated by all eight models agree reasonably well with the observed VLISM energy spectra for the elements with $Z$ from $1-28$ and with the isotopes with $Z$ from $1-14$. However, in all models it was necessary to add contributions from a primary source of $^2$H and B.

Authors

Igor Moskalenko Alan Cummings (California Institute of Technology) Dr Bryant Heikkila (NASA Goddard Space Flight Center) Guðlaugur Jóhannesson Troy Porter

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