Dependence of X-Ray Burst Models on Nuclear Masses

Schatz, H.; Ong, Wei Jia

doi:10.3847/1538-4357/aa7de9

Cited by 64 publications

(71 citation statements)

References 65 publications

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“…It should also be noted that the initial composition, and therefore the nuclear physics of hydrogen and helium burning, either in X-ray bursts or in steady state burning, is important. Cyburt et al (2016) recently determined the relevant nuclear reaction rate uncertainties in X-ray bursts, and Schatz & Ong (2017) the critical nuclear masses in X-ray bursts. More work needs to be done to explore the critical nuclear physics for a broader range of burning regimes.…”

Section: Discussionmentioning

confidence: 99%

Nuclear Reactions in the Crusts of Accreting Neutron Stars

Lau

Beard

Gupta

et al. 2018

ApJ

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139

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X-ray observations of transiently accreting neutron stars during quiescence provide information about the structure of neutron star crusts and the properties of dense matter. Interpretation of the observational data requires an understanding of the nuclear reactions that heat and cool the crust during accretion, and define its nonequilibrium composition. We identify here in detail the typical nuclear reaction sequences down to a depth in the inner crust where the mass density is ρ = 2 × 10 12 g cm −3 using a full nuclear reaction network for a range of initial compositions. The reaction sequences differ substantially from previous work. We find a robust reduction of crust impurity at the transition to the inner crust regardless of initial composition, though shell effects can delay the formation of a pure crust somewhat to densities beyond ρ = 2 × 10 12 g cm −3 . This naturally explains the small inner crust impurity inferred from observations of a broad range of systems. The exception are initial compositions with A ≥ 102 nuclei, where the inner crust remains impure with an impurity parameter of Q imp ≈ 20 due to the N = 82 shell closure. In agreement with previous work we find that nuclear heating is relatively robust and independent of initial composition, while cooling via nuclear Urca cycles in the outer crust depends strongly on initial composition. This work forms a basis for future studies of the sensitivity of crust models to nuclear physics and provides profiles of composition for realistic crust models.

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Section: Discussionmentioning

confidence: 99%

Nuclear Reactions in the Crusts of Accreting Neutron Stars

Lau

Beard

Gupta

et al. 2018

ApJ

Self Cite

139

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“…It is likely that constraining other nuclear reaction rates will require comparisons to more observable properties and many more model calculations due to their more subtle impacts on the X-ray burst light curve (Cyburt et al 2016). Logically, such investigations may be extended to nuclear masses as well (Schatz & Ong 2017).…”

Section: Discussionmentioning

confidence: 99%

Consistent Modeling of GS 1826-24 X-Ray Bursts for Multiple Accretion Rates Demonstrates the Possibility of Constraining rp-process Reaction Rates

Meisel

2018

ApJ

116

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Type-I X-ray burst light curves encode unique information about the structure of accreting neutron stars and the nuclear reaction rates of the rp-process that powers bursts. Using the first model calculations of hydrogen/helium burning bursts for a large range of astrophysical conditions performed with the code MESA, this work shows that simultaneous model-observation comparisons for bursts from several accretion ratesṀ are required to remove degeneracies in astrophysical conditions that otherwise reproduce bursts for a singleṀ and that such consistent multi-epoch modeling could possibly limit the 15 O(α, γ) 19 Ne reaction rate. Comparisons to the year 1998, 2000, and 2007 bursting epochs of the neutron star GS 1826-24 show thatṀ must be larger than previously inferred and that the shallow heating in this source must be below 0.5 MeV/u, providing a new method to constrain the shallow heating mechanism in the outer layers of accreting neutron stars. Features of the light curve rise are used to demonstrate that a lower-limit could likely be placed on the 15 O(α, γ) reaction rate, demonstrating the possibility of constraining nuclear reaction rates with X-ray burst light curves. arXiv:1805.05552v1 [astro-ph.HE]

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“…Finally, it would be interesting to extend the present work to other nuclear physics uncertainties that have been shown to impact the X-ray burst light curve, e.g. nuclear masses (del Santo et al 2014;Schatz & Ong 2017).…”

Section: Implications For Neutron Star Mass-radius Ratiomentioning

confidence: 98%

Influence of Nuclear Reaction Rate Uncertainties on Neutron Star Properties Extracted from X-Ray Burst Model–Observation Comparisons

Meisel

Merz

Medvid

2019

ApJ

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Type-I X-ray bursts can be used to determine properties of accreting neutron stars via comparisons between model calculations and astronomical observations, exploiting the sensitivity of models to astrophysical conditions. However, the sensitivity of models to nuclear physics uncertainties calls into question the fidelity of constraints derived in this way. Using X-ray burst model calculations performed with the code MESA, we investigate the impact of uncertainties for nuclear reaction rates previously identified as influential and compare them to the impact of changes in astrophysical conditions, using the conditions that are thought to best reproduce the source GS 1826-24 as a baseline. We find that reaction rate uncertainties are unlikely to significantly change conclusions about the properties of accretion onto the neutron star surface for this source. However, we find that reaction rate uncertainties significantly hinder the possibility of extracting the neutron star mass-radius ratio by matching the modeled and observed light curves due to the influence of reaction rates on the modeled light curve shape. Particularly influential nuclear reaction rates are 15 O(α, γ) and 23 Al(p, γ), though other notable impacts arise from 14 O(α, p), 18 Ne(α, p), 22 Mg(α, p), 24 Mg(α, γ), 59 Cu(p, γ), and 61 Ga(p, γ). Furthermore, we find that varying some nuclear reaction rates within their uncertainties has an impact on the neutron star crust composition and thermal structure that is comparable to relatively significant changes accretion conditions. arXiv:1812.07155v1 [astro-ph.HE]

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Dependence of X-Ray Burst Models on Nuclear Masses

Cited by 64 publications

References 65 publications

Nuclear Reactions in the Crusts of Accreting Neutron Stars

Nuclear Reactions in the Crusts of Accreting Neutron Stars

Consistent Modeling of GS 1826-24 X-Ray Bursts for Multiple Accretion Rates Demonstrates the Possibility of Constraining rp-process Reaction Rates

Influence of Nuclear Reaction Rate Uncertainties on Neutron Star Properties Extracted from X-Ray Burst Model–Observation Comparisons

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