Uncertainties in the production of<i>p</i>nuclei in massive stars obtained from Monte Carlo variations

Abstract

Nuclear data uncertainties in the production of p nuclei in massive &#13;\nstars have been quantified in a Monte Carlo procedure. Bespoke&#13;\ntemperature-dependent uncertainties were assigned to different types of&#13;\nreactions involving nuclei from Fe to Bi. Their simultaneous impact was&#13;\nstudied in post-processing explosive trajectories for three different&#13;\nstellar models. It was found that the grid of mass zones in the model of&#13;\na 25 M⊙ star, which is widely used for investigations of&#13;\np nucleosynthesis, is too crude to properly resolve the detailed&#13;\ntemperature changes required for describing the production of p nuclei.&#13;\nUsing models with finer grids for 15 and 25 M⊙ stars with&#13;\ninitial solar metallicity, it was found that most of the production&#13;\nuncertainties introduced by nuclear reaction uncertainties are smaller&#13;\nthan a factor of 2. Since a large number of rates were varied at the&#13;\nsame time in the Monte Carlo procedure, possible cancellation effects of&#13;\nseveral uncertainties could be taken into account. Key rates were&#13;\nidentified for each p nucleus, which provide the dominant contribution&#13;\nto the production uncertainty. These key rates were found by examining&#13;\ncorrelations between rate variations and resulting abundance changes.&#13;\nThis method is superior to studying flow patterns, especially when the&#13;\nflows are complex, and to individual, sequential variation of a few&#13;\nrates.