The impact of (n,$gamma$) reaction rate uncertainties of unstable isotopes on the i-process nucleosynthesis of the elements from Ba to W. (arXiv:2010.15798v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Denissenkov_P/0/1/0/all/0/1">Pavel A. Denissenkov</a> (UVic), <a href="http://arxiv.org/find/astro-ph/1/au:+Herwig_F/0/1/0/all/0/1">Falk Herwig</a> (UVic), <a href="http://arxiv.org/find/astro-ph/1/au:+Perdikakis_G/0/1/0/all/0/1">Georgios Perdikakis</a> (CMU), <a href="http://arxiv.org/find/astro-ph/1/au:+Schatz_H/0/1/0/all/0/1">Hendrik Schatz</a> (MSU)
The anomalous abundances of n-capture elements in the CEMP-r/s stars agree in
many instances very well with simulation predictions of intermediate n-density
nucleosynthesis, $N_mathrm{n}sim 10^{13}$ – $10^{15} mathrm{cm}^{-3}$, in
rapidly-accreting white dwarfs (RAWDs). We have performed Monte-Carlo
simulations of this i-process nucleosynthesis in order to determine the impact
of (n,$gamma$) reaction rate uncertainties of 164 unstable isotopes, from
$^{131}$I to $^{189}$Hf, on the prediction of abundances of 18 elements from Ba
to W. The impact study is based on two representative one-zone models with
constant values of $N_mathrm{n} = 3.16times 10^{14} mathrm{cm}^{-3}$ and
$N_mathrm{n} = 3.16times 10^{13} mathrm{cm}^{-3}$ and on a multi-zone
simulation based on a realistic stellar evolution model of He-shell convection
entraining H in a RAWD model with [Fe/H]$,=-2.6$. For each of the selected
elements, we have identified up to two (n,$gamma$) reactions having the
strongest correlations between their rate variations constrained by
Hauser-Feshbach computations and the predicted abundances, with the Pearson
product-moment correlation coefficients $|r_mathrm{P}| > 0.15$. We find that
the possible discrepancies between the predicted and observed abundances of Ba
and Pr in the CEMP-r/s star CS31062-050 could be significantly diminished if
the rate of the reaction $^{137}$Cs(n,$gamma)^{138}$Cs were reduced and the
rates of $^{141}$Ba(n,$gamma)^{142}$Ba or $^{141}$La(n,$gamma)^{142}$La
increased. (abridged)
The anomalous abundances of n-capture elements in the CEMP-r/s stars agree in
many instances very well with simulation predictions of intermediate n-density
nucleosynthesis, $N_mathrm{n}sim 10^{13}$ – $10^{15} mathrm{cm}^{-3}$, in
rapidly-accreting white dwarfs (RAWDs). We have performed Monte-Carlo
simulations of this i-process nucleosynthesis in order to determine the impact
of (n,$gamma$) reaction rate uncertainties of 164 unstable isotopes, from
$^{131}$I to $^{189}$Hf, on the prediction of abundances of 18 elements from Ba
to W. The impact study is based on two representative one-zone models with
constant values of $N_mathrm{n} = 3.16times 10^{14} mathrm{cm}^{-3}$ and
$N_mathrm{n} = 3.16times 10^{13} mathrm{cm}^{-3}$ and on a multi-zone
simulation based on a realistic stellar evolution model of He-shell convection
entraining H in a RAWD model with [Fe/H]$,=-2.6$. For each of the selected
elements, we have identified up to two (n,$gamma$) reactions having the
strongest correlations between their rate variations constrained by
Hauser-Feshbach computations and the predicted abundances, with the Pearson
product-moment correlation coefficients $|r_mathrm{P}| > 0.15$. We find that
the possible discrepancies between the predicted and observed abundances of Ba
and Pr in the CEMP-r/s star CS31062-050 could be significantly diminished if
the rate of the reaction $^{137}$Cs(n,$gamma)^{138}$Cs were reduced and the
rates of $^{141}$Ba(n,$gamma)^{142}$Ba or $^{141}$La(n,$gamma)^{142}$La
increased. (abridged)
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