Lithium-Beryllium-Boron Evolution: From Meneguzzi, Audouze and Reeves 1971 Up to Now

We review the main sources of LiBeB production and show that a primary mechanism is at work in the early Galaxy involving both ejection and acceleration of He, C and O at moderate energy, which by nuclear interaction with H and He produce light isotopes. The precise measurement of the Be abundance at [Fe/H] = -3.3 and of $^6Li$ in halo stars find an explanation in this framework. Thus, the preservation of $^6Li$ in the atmosphere of metal poor stars implied, points toward the fact the Spite plateau reflects the primordial value of Li. Consequently, it can be used as a baryodensitometer.Comment: 6 pages, no figure, invited talk, to be published in World Scientific, Proceedings of the conference "Cosmic Evolution" in the honor of Jean Audouze and James W. Truran, held at the Institut d'Astrophysique de Paris, Franc

The Primordial Lithium Problem

Big-bang nucleosynthesis (BBN) theory, together with the precise WMAP cosmic baryon density, makes tight predictions for the abundances of the lightest elements. Deuterium and 4He measurements agree well with expectations, but 7Li observations lie a factor 3-4 below the BBN+WMAP prediction. This 4-5\sigma\ mismatch constitutes the cosmic "lithium problem," with disparate solutions possible. (1) Astrophysical systematics in the observations could exist but are increasingly constrained. (2) Nuclear physics experiments provide a wealth of well-measured cross-section data, but 7Be destruction could be enhanced by unknown or poorly-measured resonances, such as 7Be + 3He -> 10C^* -> p + 9B. (3) Physics beyond the Standard Model can alter the 7Li abundance, though D and 4He must remain unperturbed; we discuss such scenarios, highlighting decaying Supersymmetric particles and time-varying fundamental constants. Present and planned experiments could reveal which (if any) of these is the solution to the problem.Comment: 29 pages, 7 figures. Per Annual Reviews policy, this is the original submitted draft. Posted with permission from the Annual Review of Nuclear and Particle Science, Volume 61. Annual Reviews, http://www.annualreviews.org . Final published version at http://www.annualreviews.org/doi/abs/10.1146/annurev-nucl-102010-13044

Updated constraint on a primordial magnetic field during big bang nucleosynthesis and a formulation of field effects

A new upper limit on the amplitude of primordial magnetic field (PMF) is derived by a comparison between a calculation of elemental abundances in big bang nucleosynthesis (BBN) model and the latest observational constraints on the abundances. Updated nuclear reaction rates are adopted in the calculation. Effects of PMF on the abundances are consistently taken into account in the numerical calculation with the precise formulation of changes in physical variables. We find that abundances of 3He and 6Li increase while that of 7Li decreases when the PMF amplitude increases, in the case of the baryon-to-photon ratio determined from the measurement of cosmic microwave background radiation. We derive a constraint on the present amplitude of PMF, i.e., B(0)<1.5 micro G [corresponding to the amplitude less than 2.0x10^{11} G at BBN temperature of T=10^9 K] based on the rigorous calculation.Comment: 26 pages, 4 figures, new observation of D/H ratio adopted, tighter constraint derived, Sec. IV modified, accepted for publication in PR

LiBeB, Cosmic Rays and Gamma-Ray Line Astronomy

This article is a summary of a recently held conference on the light elements, Li, Be and B, and their relationship to cosmic-ray origin and gamma-ray astronomy. The proceedings will be published by the PASP.Comment: latex 6 pages, uses aasms4.sty To appear in the Publications of the Astronomical Society of the Pacific (PASP

Big-bang nucleosynthesis with the NACRE compilation

We update the Big Bang Nucleosynthesis (BBN) calculations on the basis of the recent NACRE compilation of reaction rates. In particular, we calculate the uncertainties related to the nuclear reaction rates on the abundances of 7Li and compare our results with an other recent analysis

Heavy Nuclei Enrichment of the Galactic Cosmic Rays at High Energy: Astrophysical Interpretation

A substantial increase of the mean logarithmic mass of galactic cosmic rays {\em vs} energy has been observed . We study three effects that could explain this trend i) different source spectra for protons and heavy nuclei ii) a selective nuclear destruction in flight of heavies iii) a gradient of the source number and chemical composition in the galactic disk. We take advantage of the diffusive cosmic ray propagation model developed at LAPTH to study specifically the geometrical aspects of the propagation and extend it to high energy. Using a simple modeling of the spectral knee around $10^{15}$ eV, a bump in appears. This feature is smoother when the spectral index of protons is steeper than Fe's. We analyze the effects of the rigidity dependence of the diffusion coefficient and the scale height of the confinement halo and we show that $<\ln A>$ is most sensitive to the first parameter. Pure geometrical effects are less determining than the diffusion coefficient spectral index. Subsequently, we conclude that the physics of cosmic ray confinement is the essential cause of the heavy nuclei enrichment until $\sim 10^{15}$ eV.Comment: 26 pages, 7 PostScript figures. Astropart. Phys, accepted; misprint in fig6 correcte

Testing Spallation Processes With Beryllium and Boron

The nucleosynthesis of Be and B by spallation processes provides unique insight into the origin of cosmic rays. Namely, different spallation schemes predict sharply different trends for the growth of LiBeB abundances with respect to oxygen. ``Primary'' mechanisms predict BeB $\propto$ O, and are well motivated by the data if O/Fe is constant at low metallicity. In contrast, ``secondary'' mechanisms predict BeB $\propto$ O$^2$ and are consistent with the data if O/Fe increases towards low metallicity as some recent data suggest. Clearly, any primary mechanism, if operative, will dominate early in the history of the Galaxy. In this paper, we fit the BeB data to a two-component scheme which includes both primary and secondary trends. In this way, the data can be used to probe the period in which primary mechanisms are effective. We analyze the data using consistent stellar atmospheric parameters based on Balmer line data and the continuum infrared flux. Results depend sensitively on Pop II O abundances and, unfortunately, on the choice of stellar parameters. When using recent results which show O/Fe increasing toward lower metallicity, a two-component Be-O fits indicates that primary and secondary components contribute equally at [O/H]$_{eq}$ = -1.8 for Balmer line data; and [O/H]$_{eq}$ = -1.4 to -1.8 for IRFM. We apply these constraints to recent models for LiBeB origin. The Balmer line data does not show any evidence for primary production. On the other hand, the IRFM data does indicate a preference for a two-component model, such as a combination of standard GCR and metal-enriched particles accelerated in superbubbles. These conclusions rely on a detailed understanding of the abundance data including systematic effects which may alter the derived O-Fe and BeB-Fe relations.Comment: 40 pages including 11 ps figures. Written in AASTe