1999/05/05 by J. P. Meyer, Meyer, J. P., Donald C. Ellison +2
Physics and Astronomy · #Astro and Planetary Science #Astrophysics (astro-ph) #FOS: Physical sciences #Gamma-ray bursts and supernovae #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9905037
21 pages, 3 figures
arxiv created 1999/05/05 · openalex publication_date 1999/05/05 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The composition of present day cosmic rays (CRs) is inconsistent with a significant acceleration of SN ejecta material (even with a preferential acceleration of ejecta grain material). Current CRs must result mainly from the acceleration of ISM ("solar mix") and circumstellar (22Ne- and 12C-rich WR wind) gas and grain material. The CR source composition, indeed, shows no anomaly related to SN nucleosynthesis: (i) The CR source FeNi/MgSiCa ratios have precisely solar mix values, while FeNi are mainly synthesized in SN Ia's, and MgSiCa in SN II's. If CR's originate in SN ejecta, this requires tight conditions on the acceleration efficiencies of the various SN Ia's and SN II's. (ii) The non-deficiency of the main-s-process elements, not made in any SN, relative to all elements made in SNae. (iii) All CR source isotope ratios are consistent with solar mix (except for the 22Ne and 12C excesses, WR wind). (iv) The absence of 59Ni in CRs implies that the time delay between the SN nucleosynthesis and their acceleration is > 105 yr. (v) The physics of SNR's and of CR shock acceleration implies that the acceleration of interior ejecta material is comparatively insignificant (Ellison & Meyer, this volume). Predominant acceleration of current CRs out of superbubble material also seems implausible. These conclusions regarding current CRs do not necessarily conflict with the linear evolution of Be/H in the early Galaxy. With the near absence of heavy elements in the early Galactic ISM, indeed, the acceleration of even a minute amount of freshly processed material must have then played a dominant role for the generation of Be from C and O. The "Be indicator" is blind to a possibly dominant early Galactic CR component originating in the ISM then composed of virtually pure H and He.