Standard Big Bang Nucleosynthesis Up to Cno With an Improved Extended Nuclear Network

Abstract

Primordial or Big Bang nucleosynthesis (BBN) is one of the three strong evidences for the Big-Bang model together with the expansion of the Universe and the Cosmic Microwave Background radiation. In this study, we improve the standard BBN calculations taking into account new nuclear physics analyses and we enlarge the nuclear network until Sodium. This is, in particular, important to evaluate the primitive value of CNO mass fraction that could affect Population III stellar evolution. For the first time we list the complete network of more than 400 reactions with references to the origin of the rates, including ≈270 reaction rates calculated using the TALYS code. Together with the cosmological light elements, we calculate the primordial Beryllium, Boron, Carbon, Nitrogen and Oxygen nuclei. We performed a sensitivity study to identify the important reactions for CNO, 9 Be and Boron nucleosynthesis. We reevaluated those important reaction rates using experimental data and/or theoretical evaluations. The results are compared with precedent calculations: a primordial Beryllium abundance increase by a factor of 4 compared to its previous evaluation, but we note a stability for B/H and for the CNO/H abundance ratio that remains close to its previous value of 0.7 × 10 −15 . On the other hand, the extension of the nuclear network has not changed the 7 Li value, so its abundance is still 3-4 times greater than its observed spectroscopic value.

Primordial Nucleosynthesis

“…There is a good agreement between the primordial abundances of 4 He and D, deduced from observations, and from primordial nucleosynthesis calculations. However, the 7 Li calculated abundance is significantly higher than the one deduced from spectroscopic observations. Solutions to this problem that have been considered include stellar surface depletion of lithium, nuclear destruction during BBN or solutions beyond the standard model (see [2] for a review).…”

“…The nuclear reaction rates are those listed in [7] with only a few updates listed below. Recently, Hou et al [14] have re-evaluated the 7 Be(n,α) 4 He cross section, based on 4 He(α,n) 7 Be, 4 He(α,p) 7 Li and 7 Li(p,α) 4 He experimental data, using charge symmetry and/or detailed balance principles. An improved evaluation of the 3 He(α, γ) 7 Be reaction rate has been published [8], using a Monte-Carlo based R-matrix analysis.…”

“…Recently, Hou et al [14] have re-evaluated the 7 Be(n,α) 4 He cross section, based on 4 He(α,n) 7 Be, 4 He(α,p) 7 Li and 7 Li(p,α) 4 He experimental data, using charge symmetry and/or detailed balance principles. An improved evaluation of the 3 He(α, γ) 7 Be reaction rate has been published [8], using a Monte-Carlo based R-matrix analysis. The effect of these re-evaluations can be seen between columns 2 and 3 in Table I, while columns 4 shows the effect of the re-evaluated reaction rates [5] for deuterium destruction (see § 3).…”

“…The effect of these re-evaluations can be seen between columns 2 and 3 in Table I, while columns 4 shows the effect of the re-evaluated reaction rates [5] for deuterium destruction (see § 3). Column 5 represent the results of a Monte Carlo calculation [5] as described in [7,9] but with these few new rates, to be compared with observations in Column 6. [5].…”

A single low-energy, iron-poor supernova as the source of metals in the star SMSS J031300.36−670839.3

“…Lithium is detected in the star at a level A(Li) = log 10 (N(Li))/N(H) + 12 = 0.7 that displays significant depletion from the primordial Big Bang level (A(Li) = 2.72) 34 . Such lithium depletion is expected within a metal-poor first ascent red giant branch star 21 due to cycling of material in regions of high temperature where lithium is destroyed and subsequent dilution in an extensive convective envelope.…”