Impact of Nuclear Reaction Rate Uncertainties on Type I X-ray Burst Nucleosynthesis: A Monte Carlo Study

TL;DR

This study uses Monte Carlo simulations to assess how uncertainties in nuclear reaction rates influence the nucleosynthesis outcomes of Type I X-ray bursts, revealing complex isotope abundance patterns.

Contribution

It introduces a comprehensive Monte Carlo approach with large reaction rate perturbations, uncovering multi-peak isotope distributions and confirming key reactions for future research.

Findings

Multi-peak abundance distributions for certain isotopes.

Large perturbations can cause multi-peak structures.

Confirmed key reactions for X-ray burst nucleosynthesis.

Abstract

Type I X-ray bursts are thermonuclear flashes on the surface of accreting neutron stars, involving hundreds of nuclei and thousands of reactions with larger uncertainties in reaction rate. To investigate the impact of nuclear reaction rate uncertainties on type I X-ray burst nucleosynthesis, comprehensive Monte Carlo simulations were performed with temperature-independent and -dependent variations in reaction rates using the REACLIB and STARLIB libraries, respectively. A total of 1,711 $(p, \gamma)$, $(p, \alpha)$, $(\alpha, p)$, and $(\alpha, \gamma)$ reaction rates are varied simultaneously along with their inverse reactions via detailed balance. For the first time, it has been found that Monte Carlo sampling with larger perturbations to these reaction rates may lead to multi-peak abundance distributions for certain isotopes, such as $^{64}$Zn and $^{55}$Co. These multi-peak structures arise not only from coupled reactions but also from single reactions in some cases. Our studies also confirm previously identified key reactions and provide more robust lists that deserve priority consideration in future studies.