2025/12/12 by N. Bhathi, J.S. Randhawa, Bhathi, N. +75
Physics and Astronomy · #Astrophysical Phenomena and Observations #FOS: Physical sciences #Gamma-ray bursts and supernovae #High Energy Astrophysical Phenomena (astro-ph.HE) #Nuclear Experiment (nucl-ex) #Pulsars and Gravitational Waves Research
paper · pdf · doi:10.48550/arxiv.2512.12025
openalex publication_date 2025/12/12 · openalex created_date 2025/12/17 · openalex updated_date 2026/07/28
Model-observation comparisons of type-I X-ray bursts (XRBs) can reveal the properties of accreting neutron star systems, including the neutron star compactness. XRBs are powered by nuclear burning and a handful of reactions have been shown to impact the model results. Reactions in the NiCu cycles, featuring a competition between 59Cu(p,γ)60Zn and 59Cu(p,α)56Ni, have been shown to be among the most important reactions as they are a critical checkpoint in rp-process flow and significantly impact the light curves and burst ashes. We report a direct measurement of 59Cu(p,α)56Ni bringing stringent constraints on this reaction rate. New results rule out a strong NiCu cycle in XRBs, with a negligible degree of recycling, ≤5% up to 1.5 GK. The new reaction rate, when varied within new uncertainty limits, shows no impact on one-zone XRB model light-curves tailored for clocked-burster \ttGS 1826-24, hence removing an important nuclear physics uncertainty in the model-observation comparison.