Constraints on Bygone Nucleosynthesis of Accreting Neutron Stars

Abstract

Nuclear burning near the surface of an accreting neutron star produces ashes that, when compressed deeper by further accretion, alter the star's thermal and compositional structure. Bygone nucleosynthesis can be constrained by the impact of compressed ashes on the thermal relaxation of quiescent neutron star transients. In particular, Urca cooling nuclei pairs in nuclear burning ashes, which cool the neutron star crust via neutrino emission from electron-capture/beta-decay cycles, provide signatures of prior nuclear burning over the ~century timescales it takes to accrete to the electron-capture depth of the strongest cooling pairs. Using crust cooling models of the accreting neutron star transient MAXI J0556-332, we show that this source likely lacked Type I X-ray bursts and superbursts >120 years ago. Reduced nuclear physics uncertainties in rp-process reaction rates and electron-capture ft-values for low-lying transitions will improve nucleosynthesis constraints using this technique.

Accepted to the Astrophysical Journal

References in corpus (9)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
• Dependence of X-Ray Burst Models on Nuclear Reaction Rates
• X-ray binaries
• Models of Type I X-ray Bursts from GS 1826-24: A Probe of rp-Process Hydrogen Burning
• Nucleosynthesis in Type I X-ray Bursts
• Superburst Models for Neutron Stars with Hydrogen and Helium-Rich Atmospheres
• A strongly heated neutron star in the transient Z source MAXI J0556-332
• Reaction Rate and Composition Dependence of the Stability of Thermonuclear Burning on Accreting Neutron Stars

Cited by in corpus (13)

• Cooling of Accretion-Heated Neutron Stars
• Influence of Nuclear Reaction Rate Uncertainties on Neutron Star Properties Extracted From X-ray Burst Model-Observation Comparisons
• Horizons: Nuclear Astrophysics in the 2020s and Beyond
• Nuclear Mass Measurements Map the Structure of Atomic Nuclei and Accreting Neutron Stars
• First direct measurement of ${}^{22}$Mg($\alpha$,p)${}^{25}$Al and implications for X-ray burst model-observation comparisons
• Urca Cooling in Neutron Star Crusts and Oceans: Effects of Nuclear Excitations
• $\beta$-decay of ${}^{61}$V and its Role in Cooling Accreted Neutron Star Crusts
• The Impacts of Neutron-Star Structure and Base Heating on Type I X-Ray Bursts and Code Comparison
• Improved Nuclear Physics Near $A=61$ Refines Urca Neutrino Luminosities in Accreted Neutron Star Crusts
• Constraining Accreted Neutron Star Crust Shallow Heating with the Inferred Depth of Carbon Ignition in X-ray Superbursts
• Spallation-altered accreted compositions for X-ray bursts: Impact on ignition conditions and burst ashes
• Weak interaction rates of $sd$-shell Urca pairs in stellar environment using a shell-model approach
• Urca Nuclide Production in Type-I X-ray Bursts and Implications for Nuclear Physics Studies