X-Ray Bursts

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

X-Ray Bursts

We present a Monte Carlo calculation of the astrophysical rate of the 15O(α,γ)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 (XRBs) using spherically symmetric, hydrodynamic simulations of an accreting neutron star. In this way the influence of the 15O(α,γ)19Ne reaction rate on the peak luminosity, recurrence time, and associated nucleosynthesis in models of Type I XRBs 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(α,γ)19Ne reaction rate do not strongly affect the predictions of this Type I XRB model.

Author: Davids, Barry; Cyburt, Richard H.; José, Jordi; Mythili, Subramanian
Journal: The Astrophysical Journal 735, 40 (2011)

Nuclear Astrophysics at ISAC with DRAGON

NovaeSupernovaeX-Ray Bursts

In his Nobel Prize acceptance speech in 1984, Prof. Willie Fowler of the California Institute of Technology, and the father of nuclear astrophysics said, "Direct measurements on short-lived radioactive nuclei and the excited states of all nuclei are impossible at the present
time. In this connection the production of radioactive ion beams holds great promise for the future"[Fow84]. It has taken a number of years to reach this point but this future promise is now here. The new ISAC facility combined with the DRAGON and TUDA experimental facilities will help realize this future.

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