The importance of Fe fragmentation for LiBeB analyses: Is a Li primary source needed to explain AMS-02 data?

Abstract

High-precision data from AMS-02 on Li, Be, and B provide the best constraints on Galactic cosmic-ray transport parameters. We re-evaluate the impact of Fe fragmentation on the Li, Be, and B modelling. We discuss the consequences on the transport parameter determination and reassess whether a primary source of Li is needed to match AMS-02 data. We renormalised several cross-section parametrisations to existing data for the most important reactions producing Li, Be, and B. We used the USINE code with these new cross-section sets to re-analyse Li/C, Be/C, and B/C AMS-02 data. We built three equally plausible cross-section sets. Compared to the initial cross-section sets, they lead to an average enhanced production of Li ($\sim 20-50\%$) and Be ($\sim 5-15\%$), while leaving the B flux mostly unchanged. In particular, Fe fragmentation is found to contribute to up to 10\% of the Li and Be fluxes. Used in the combined analysis of AMS-02 Li/C, Be/C, and B/C data, the fit is significantly improved, with an enhanced diffusion coefficient ($\sim 20\%)$. The three updated cross-section sets are found to either slightly undershoot or overshoot the Li/C and B/C ratios: this strongly disfavours evidence for a primary source of Li in cosmic rays. We stress that isotopic cosmic-ray ratios of Li (and to a lesser extent Be), soon to be released by AMS-02, are also impacted by the use of these updated sets. Almost no nuclear data exist for the production of Li and B isotopes from Ne, Mg, Si, and Fe, whereas these reactions are estimated to account for $\sim 20\%$ of the total production. New nuclear measurements would be appreciated and help to better exploit the high-precision AMS-02 cosmic-ray data.

20 pages, 16 figures, 2 tables (matches accepted A&A version): corrected sign for ${\delta }_l$ (typo in plotting script) + couple of sentences added (XS modelling, results for various propagation configurations)

References in corpus (20)

• Galactic cosmic rays after the AMS-02 observations
• Indications for a high-rigidity break in the cosmic-ray diffusion coefficient
• Cosmic-ray transport from AMS-02 B/C data: benchmark models and interpretation
• Spallation Residues in the Reaction 56Fe + p at 0.3, 0.5, 0.75, 1.0 and 1.5 A GeV
• Galactic halo size in the light of recent AMS-02 data
• Direct Measurement of the Cosmic-Ray Carbon and Oxygen Spectra from 10 GeV$/n$ to 2.2 TeV$/n$ with the Calorimetric Electron Telescope on the International Space Station
• Implications of current nuclear cross sections on secondary cosmic rays with the upcoming DRAGON2 code
• Implications of Lithium to Oxygen AMS-02 spectra on our understanding of cosmic-ray diffusion
• Measurement of the Iron Spectrum in Cosmic Rays from 10 GeV$/n$ to 2.0 TeV$/n$ with the Calorimetric Electron Telescope on the International Space Station
• p, He, and C to Fe cosmic-ray primary fluxes in diffusion models: Source and transport signatures on fluxes and ratios
• Cross-sections for nuclide production in 56Fe target irradiated by 300, 500,750, 1000, 1500, and 2600 MeV protons compared with data on hydrogen target irradiation by 300, 500, 750, 1000, and 1500 MeV/nucleon 56Fe ions
• Markov chain Monte Carlo analyses of the flux ratios of B, Be and Li with the DRAGON2 code
• New minimal, median, and maximal propagation models for dark matter searches with Galactic cosmic rays
• Explaining cosmic ray antimatter with secondaries from old supernova remnants
• Bayesian evaluation of residual production cross sections in proton induced spallation reactions
• A simple determination of the halo size $L$ from ${}^{10}$Be/${}^9$Be data
• Cosmic-Ray Lithium Production at the Nova Eruption Followed by a Type Ia Supernova
• The rigidity dependence of galactic cosmic-ray fluxes and its connection with the diffusion coefficient
• Origin of Spectral Hardening of Secondary Cosmic-Ray Nuclei
• Light fragment and neutron emission in high-energy proton induced spallation reactions

Cited by in corpus (5)

• A simple determination of the halo size $L$ from ${}^{10}$Be/${}^9$Be data
• Can the Production Cross-Section Uncertainties Explain the Cosmic Fluorine Anomaly?
• Current status and desired accuracy of the isotopic production cross-sections relevant to astrophysics of cosmic rays II. Fluorine to Silicon (and updated LiBeB)
• The AMS-02 cosmic ray deuteron flux is consistent with a secondary origin
• Transport parameters from AMS-02 F/Si data and fluorine source abundance