Z. Meisel

THE JINA REACLIB DATABASE: ITS RECENT UPDATES AND IMPACT ON TYPE-I X-RAY BURSTS

We present results from the JINA REACLIB project, an ongoing effort to maintain a current and accurate library of thermonuclear reaction rates for astrophysical applications. Ongoing updates are transparently documented and version tracked, and any set of rates is publicly available and can be downloaded via a Web interface at http://groups.nscl.msu.edu/jina/reaclib/db/. We discuss here our library V1.0, a snapshot of recommended rates for stable and explosive hydrogen and helium burning. We show that the updated reaction rates lead to modest but significant changes in full network, one-dimensional X-ray burst model calculations, compared with calculations with previously used reaction rate sets. The late time behavior of X-ray burst light curves shows significant changes, suggesting that the previously found small discrepancies between model calculations and observations may be solved with a better understanding of the nuclear input. Our X-ray burst model calculations are intended to serve as a benchmark for future model comparisons and sensitivity studies, as the complete underlying nuclear physics is fully documented and publicly available.

DEPENDENCE OF X-RAY BURST MODELS ON NUCLEAR REACTION RATES

X-ray bursts are thermonuclear flashes on the surface of accreting neutron stars and reliable burst models are needed to interpret observations in terms of properties of the neutron star and the binary system. We investigate the dependence of X-ray burst models on uncertainties in (p,

Urca cooling pairs in the neutron star ocean and their effect on superbursts

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Mass Measurement of 56Sc Reveals a Small A = 56 Odd-Even Mass Staggering, Implying a Cooler Accreted Neutron Star Crust

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Isobaric multiplet mass equation in the A = 31 , T = 3 / 2 quartets

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Mass Measurements Demonstrate a Strong N = 28 Shell Gap in Argon

,

A gas jet target for radioactive ion beam experiments

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Low-lying level structure of Cu 56 and its implications for the rp process

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Isospin Mixing Reveals P 30 (p,γ) S 31 Resonance Influencing Nova Nucleosynthesis

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Time-of-flight mass measurements of neutron-rich chromium isotopes up to N = 40 and implications for the accreted neutron star crust

,p) nuclear reaction rates using fully self-consistent burst models that account for the feedbacks between changes in nuclear energy generation and changes in astrophysical conditions. A two-step approach first identified sensitive nuclear reaction rates in a single-zone model with ignition conditions chosen to match calculations with a state-of-the-art 1D multi-zone model based on the {\Kepler} stellar evolution code. All relevant reaction rates on neutron deficient isotopes up to mass 106 were individually varied by a factor of 100 up and down. Calculations of the 84 highest impact reaction rate changes were then repeated in the 1D multi-zone model. We find a number of uncertain reaction rates that affect predictions of light curves and burst ashes significantly. The results provide insights into the nuclear processes that shape X-ray burst observables and guidance for future nuclear physics work to reduce nuclear uncertainties in X-ray burst models.