The Influence of Uncertainties in the 15O(alpha,gamma)19Ne Reaction Rate on Models of Type I X-Ray Bursts

TL;DR

This study uses Monte Carlo simulations to evaluate the impact of uncertainties in the 15O(alpha,gamma)19Ne reaction rate on Type I X-ray burst models, finding minimal influence on key burst properties.

Contribution

It provides a comprehensive Monte Carlo-based assessment of reaction rate uncertainties and their negligible effect on X-ray burst predictions, challenging previous assumptions.

Findings

Reaction rate uncertainties have limited impact on burst luminosity and recurrence time.

Simulated burst properties show variations are within natural burst-to-burst fluctuations.

Uncertainty in the reaction rate does not significantly alter nucleosynthesis outcomes.

Abstract

We present a Monte Carlo calculation of the astrophysical rate of the 15O(alpha,gamma)19Ne reaction based on an evaluation of published experimental data. By considering the likelihood distributions of individual resonance parameters derived from measurements, estimates of upper and lower limits on the reaction rate at the 99.73% confidence level are derived in addition to the recommended, median value. These three reaction rates are used as input for three separate calculations of Type I x-ray bursts using spherically symmetric, hydrodynamic simulations of an accreting neutron star. In this way the influence of the 15O(alpha,gamma)19Ne reaction rate on the peak luminosity, recurrence time, and associated nucleosynthesis in models of Type I x-ray bursts is studied. Contrary to previous findings, no substantial effect on any of these quantities is observed in a sequence of four bursts when varying the reaction rate between its lower and upper limits. Rather, the differences in these quantities are comparable to the burst-to-burst variations with a fixed reaction rate, indicating that uncertainties in the 15O(alpha,gamma)19Ne reaction rate do not strongly affect the predictions of this Type I x-ray burst model.