2019ApJS..245...30L

Galactic cosmic-ray source compositions, (Z/H)_GCRS from H to Pb and ∼10⁸-10¹⁴ eV, differ from solar-local interstellar (Z/H)_SS or (Z/H)_ISM by ∼20-200x. Both are mostly just mixes of core-collapse (CCSN) and thermonuclear (SN Ia) supernova ejecta. The (Z/H)_ISM comes from steady unbiased accumulation over gigayears. But the cosmic-ray mass mixing ratio, universal interstellar medium (ISM)/CCSN ∼4:1 of swept-up ISM, and ∼10x metallicity ejecta show that (Z/H)_GCRS comes from basic Sedov-Taylor bulk mixing of homologous, expanding CCSNe in their OB-cluster self-generated superbubbles, further enriched by highly biased grain-sputtering injection during diffusive shock acceleration (DSA). Moreover, this mixing ratio now reveals that the cosmic rays are primarily accelerated as their evolving reverse-shock radius and energy pass through their maxima. Refractories and volatiles, first deposited in fast ejecta and ISM grains in freely expanding ejecta, are simultaneously Coulomb-sputtered F_CS by turbulent H and He as suprathermal ions into DSA that carries them to cosmic-ray energies. This bulk mixing selectively increases source mix abundances (Z/H)_SM/(Z/H)_SS by ∼2-10, and injection by grain condensation and implantation fractions F_GC by another ∼6, while Z^2/3-Coulomb grain sputtering enrichments F_CS give an added ∼4-20. Applying these basic processes of mixing and injection to solar system (Z/H)_SS produces grain-injected, source mix (Z/H)_SMGI values that match major cosmic-ray abundances (Z/H)_GCRS to ±35% with no free parameters. Independently confirming grain injection, we find (Z/H)_GCRS shows no detectable contribution of Fe from SN Ia, although producing ∼1/2 Fe in the ISM, but there is also no dust in SN Ia remnants, unlike CCSNe.