Voyager 1 Observations of Galactic Cosmic Rays in the Local Interstellar Medium

Voyager 1 crossed into the local interstellar medium in August 2012. The low-energy part of the energy spectra of Galactic cosmic rays (GCRs) was revealed for the first time, previously having been excluded from observation by the effects of solar modulation. We present the GCR energy spectra of most elements from H through Ni from $\sim$3 to a few hundred MeV nuc$^{-1}$, and also of electrons from 2.7 to 74 MeV, for a period exceeding two years. We find that the H and He spectra have the same energy dependence between 3 and 346 MeV nuc$^{-1}$, with a broad maximum in the10-50 MeV nuc$^{-1}$ range and a H/He ratio of 12.2 $\pm$ 0.9. The observed local interstellar gradient of 3--346 MeV H is $-0.009\pm0.055$ \%/AU. The energy spectrum of electrons ($e^-$ + $e^+$) is consistent with $E^{-1.30 \pm 0.05}$. Propagation model fits to the observed spectra allow estimates of the energy density of GCRs and the ionization rates of atomic H, which will be presented and discussed. The propagation model fits also provide improved estimates of the elemental abundances in the source of Galactic cosmic rays.