Hydrodynamic Models of Type I X-Ray Bursts: Metallicity Effects

Abstract

Type I X-ray bursts are thermonuclear stellar explosions driven by charged-particle reactions. In the regime for combined H/He-ignition, the main nuclear flow is dominated by the rp-process (rapid proton-captures and beta+ decays), the 3 alpha-reaction, and the alpha-p-process (a suite of (alpha,p) and (p,gamma) reactions). The main flow is expected to proceed away from the valley of stability, eventually reaching the proton drip-line beyond A = 38. Detailed analysis of the relevant reactions along the main path has only been scarcely addressed, mainly in the context of parameterized one-zone models. In this paper, we present a detailed study of the nucleosynthesis and nuclear processes powering type I X-ray bursts. The reported 11 bursts have been computed by means of a spherically symmetric (1D), Lagrangian, hydrodynamic code, linked to a nuclear reaction network that contains 325 isotopes (from 1H to 107Te), and 1392 nuclear processes. These evolutionary sequences, followed from the onset of accretion up to the explosion and expansion stages, have been performed for 2 different metallicities to explore the dependence between the extension of the main nuclear flow and the initial metal content. We carefully analyze the dominant reactions and the products of nucleosynthesis, together with the the physical parameters that determine the light curve (including recurrence times, ratios between persistent and burst luminosities, or the extent of the envelope expansion). Results are in qualitative agreement with the observed properties of some well-studied bursting sources. Leakage from the predicted SbSnTe-cycle cannot be discarded in some of our models. Production of 12C (and implications for the mechanism that powers superbursts), light p-nuclei, and the amount of H left over after the bursting episodes will also be discussed.

78 pages (pdf), including 34 figures. Accepted for publication in The Astrophysical Journal Suppl. Series

References in corpus (8)

• Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
• X-ray binaries
• The Effects of Variations in Nuclear Processes on Type I X-Ray Burst Nucleosynthesis
• Models of Type I X-ray Bursts from GS 1826-24: A Probe of rp-Process Hydrogen Burning
• The ${}^{15}$O($\alpha$,$\gamma$)${}^{19}$Ne Breakout Reaction and Impact on X-Ray Bursts
• Production and $\beta$ decay of rp-process nuclei ${}^{96}$Cd, ${}^{98}$In and ${}^{100}$Sn
• A Spectroscopic Study of Nuclear Processing and Production of Anomalously Strong Lines in the Crab Nebula
• Accretion rate and the occurrence of multi-peaked X-ray bursts

Cited by in corpus (46)

• Dependence of X-Ray Burst Models on Nuclear Reaction Rates
• Frontiers in Nuclear Astrophysics
• Nucleosynthesis in Type I X-ray Bursts
• Thermonuclear X-ray bursts
• Nuclear Physics of the Outer Layers of Accreting Neutron Stars
• Nuclear astrophysics: the unfinished quest for the origin of the elements
• Observatory science with eXTP
• Nuclear Reactions in the Crusts of Accreting Neutron Stars
• Dependence of X-ray Burst Models on Nuclear Masses
• Consistent Modeling of GS 1826-24 X-ray Bursts for Multiple Accretion Rates Demonstrates the Possibility to Constrain rp-process Reaction Rates
• Horizons: Nuclear Astrophysics in the 2020s and Beyond
• The influence of accretion rate and metallicity on thermonuclear bursts: predictions from KEPLER models
• Thermonuclear Bursts with Short Recurrence Times from Neutron Stars Explained by Opacity-Driven Convection
• Reaction Rate and Composition Dependence of the Stability of Thermonuclear Burning on Accreting Neutron Stars
• Multi-epoch X-ray burst modelling: MCMC with large grids of 1D simulations
• The Influence of Uncertainties in the 15O(alpha,gamma)19Ne Reaction Rate on Models of Type I X-Ray Bursts
• Multidimensional Modeling of Type I X-ray Bursts. II. Two-Dimensional Convection in a Mixed H/He Accretor
• Absolute Determination of the 22Na(p,g) Reaction Rate in Novae
• Constraints on Bygone Nucleosynthesis of Accreting Neutron Stars
• Reaction rates of ${}^{64}$Ge($p,\gamma$)${}^{65}$As and ${}^{65}$As($p,\gamma$)${}^{66}$Se and the extent of nucleosynthesis in type I X-ray bursts
• Neutron star cooling and the rp process in thermonuclear X-ray bursts
• Carbon Synthesis in Steady-State Hydrogen and Helium Burning On Accreting Neutron Stars
• $\beta$-decay of ${}^{61}$V and its Role in Cooling Accreted Neutron Star Crusts
• Thermonuclear X-ray Bursts with late secondary peaks observed from 4U 1608-52
• Relative proton and gamma widths of astrophysically important states in 30S studied in the beta-decay of 31Ar
• Spectroscopy of ${}^{19}$Ne for the thermonuclear ${}^{15}$O($\alpha ,\gamma$)${}^{19}$Ne and ${}^{18}$F($p,\alpha$)${}^{15}$O reaction rates
• Mass-loss and composition of wind ejecta in type I X-ray bursts
• Performance Improvements for Nuclear Reaction Network Integration
• Dynamics of Laterally Propagating Flames in X-ray Bursts. I. Burning Front Structure
• The Impacts of Neutron-Star Structure and Base Heating on Type I X-Ray Bursts and Code Comparison
• First direct measurement constraining the ${}^{34}$Ar($\alpha$,p)${}^{37}$K reaction cross section for mixed hydrogen and helium burning in accreting neutron stars
• Single neutron transfer on 23Ne and its relevance forthepathway ofnucleosynthesis in astrophysical X-ray bursts
• Simulations of stellar winds from X-ray bursts. Characterization of solutions and observable variables
• New 26P(p,γ)27S thermonuclear reaction rate and its astrophysical implication in rp-process
• Hydrodynamical simulations of proton ingestion flashes in Type I X-ray Bursts
• Spallation-altered accreted compositions for X-ray bursts: Impact on ignition conditions and burst ashes
• Modelling Thermonuclear X-ray Bursts on Accreting Neutron Stars
• Proton capture on ${}^{30}$P in novae: On the existence of states at $6.40$ MeV and $6.65$ MeV in ${}^{31}$S
• On the parallelization of stellar evolution codes
• Improved thermonuclear rate of ${}^{42}$Ti($p$,$\gamma$)${}^{43}$V and its astrophysical implication in rp-process
• New ${}^{63}$Ga(p,$\gamma$)${}^{64}$Ge and ${}^{64}$Ge(p,$\gamma$)${}^{65}$As reaction rates corresponding to the temperature regime of thermonuclear X-ray bursts
• Nucleosynthesis in Type Ia Supernovae, Classical Novae, and Type I X-Ray Bursts. A Primer on Stellar Explosions
• Nuclear astrophysics
• Reevaluation of thermonuclear reaction rate of 50Fe(p,gamma)51Co
• Neutron star atmospheres composed of fusion ashes
• Urca Nuclide Production in Type-I X-ray Bursts and Implications for Nuclear Physics Studies