Long Type I X-ray Bursts and Neutron Star Interior Physics

Abstract

Superbursts are very energetic Type I X-ray bursts discovered in recent years by long term monitoring of X-ray bursters, believed to be due to unstable ignition of carbon in the deep ocean of the neutron star. A number of "intermediate duration" bursts have also been observed, probably associated with ignition of a thick helium layer. We investigate the sensitivity of these long X-ray bursts to the thermal profile of the neutron star crust and core. We first compare cooling models of superburst lightcurves with observations, and derive constraints on the ignition mass and energy release, and then calculate ignition models for superbursts and pure helium bursts, and compare to observations. The superburst lightcurves and ignition models imply that the carbon mass fraction is approximately 20% or greater in the fuel layer, constraining models of carbon production. However, the most important result is that when Cooper pairing neutrino emission is included in the crust, the temperature is too low to support unstable carbon ignition at the observed column depths. Some additional heating mechanism is required in the accumulating fuel layer to explain the observed properties of superbursts. If Cooper pair emission is less efficient than currently thought, the observed ignition depths for superbursts imply that the crust is a poor conductor, and the core neutrino emission is not more efficient than modified URCA. The observed properties of helium bursts support these conclusions, requiring inefficient crust conductivity and core neutrino emission.

arXiv commentsubmitted to ApJ (22 pages, 26 figures)

References in corpus (46)

• Neutron Star Cooling
• Minimal Cooling of Neutron Stars: A New Paradigm
• The endpoint of the rp process on accreting neutron stars
• Evolutionary Binary Sequences for Low- and Intermediate-Mass X-ray Binaries
• Crustal Heating and Quiescent Emission from Transiently Accreting Neutron Stars
• Models for Type I X-Ray Bursts with Improved Nuclear Physics
• A Remarkable Three Hour Thermonuclear Burst From 4U 1820-30
• Carbon Flashes in the Heavy Element Ocean on Accreting Neutron Stars
• The rp Process Ashes from Stable Nuclear Burning on an Accreting Neutron Star
• The Ocean and Crust of a Rapidly Accreting Neutron Star: Implications for Magnetic Field Evolution and Thermonuclear Flashes
• Equation of state of fully ionized electron-ion plasmas. II. Extension to relativistic densities and to the solid phase
• Renormalization group approach to neutron matter: quasiparticle interactions, superfluid gaps and the equation of state
• Nuclear composition and heating in accreting neutron-star crusts
• Crustal Emission and the Quiescent Spectrum of the Neutron Star in KS 1731-260
• Rotational Evolution During Type I X-Ray Bursts
• Nuclear fusion in dense matter: Reaction rate and carbon burning
• Evidence for a Millisecond Pulsar in 4U 1636-53 During a Superburst
• Periodic Thermonuclear X-ray Bursts from GS 1826-24 and the Fuel Composition as a Function of Accretion Rate
• On the possibility of a helium white dwarf donor in the presumed ultracompact binary 2S 0918-549
• Models of Type I X-Ray Bursts in 4U 1820-30
• Charting the temperature of the Hot Neutron Star in a Soft X-ray Transient
• Optical spectra of the carbon-oxygen accretion discs in the ultra-compact X-ray binaries 4U 0614+09, 4U 1543-624 and 2S 0918-549
• Ultracompact X-Ray Binaries with Neon-Rich Degenerate Donors
• Nearly Coherent Oscillations in Type I X-Ray Bursts from KS 1731-260
• Nuclear heating and melted layers in the inner crust of an accreting neutron star
• Thermonuclear Stability of Material Accreting onto a Neutron Star
• A half-a-day long thermonuclear X-ray burst from KS 1731-260
• XMM-Newton observations of the neutron star X-ray transient KS 1731-260 in quiescence
• A superburst from 4U 1254-690
• The Thermal Evolution following a Superburst on an Accreting Neutron Star
• Thermal states of coldest and hottest neutron stars in soft X-ray transients
• Recurrent very-long type-I X-ray bursts in the low-mass X-ray binary 4U 1636-53
• Superfluid Properties of the Inner Crust of Neutron Stars
• Superburst Ignition and Implications for Neutron Star Interiors
• Thermonuclear X-ray Bursts: Theory vs. Observations
• Theory and Observations of Type I X-Ray Bursts from Neutron Stars
• Superbursts at near-Eddington mass accretion rates
• Theoretical Models of Superbursts on Accreting Neutron Stars
• A four-hours long burst from Serpens X-1
• Superbursts from Strange Stars
• Discovery of the neutron star nature of SLX 1737-282
• Hydrostatic Expansion and Spin Changes During Type I X-Ray Bursts
• What we can learn from observations of cooling neutron stars
• Mean field and pairing properties in the crust of neutron stars
• Heterogeneity of solid neutron-star matter: transport coefficients and neutrino emissivity
• Symmetry of the Neutron and Proton Superfluidity Effects in Cooling Neutron Stars

Cited by in corpus (133)

• Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
• Physics of Neutron Star Crusts
• The Progenitors of Short Gamma-Ray Bursts
• Mapping crustal heating with the cooling lightcurves of quasi-persistent transients
• Thermonuclear burst oscillations
• Neutrino Emission from Cooper Pairs and Minimal Cooling of Neutron Stars
• Heating in the Accreted Neutron Star Ocean: Implications for Superburst Ignition
• 2D Cooling of Magnetized Neutron Stars
• Six new candidate ultracompact X-ray binaries
• Coulomb tunneling for fusion reactions in dense matter: Path integral Monte Carlo versus mean field
• Dependence of X-Ray Burst Models on Nuclear Reaction Rates
• The Multi-INstrument Burst ARchive (MINBAR)
• Strong neutrino cooling by cycles of electron capture and ${\beta }^{-}$ decay in neutron star crusts
• Helium-rich thermonuclear bursts and the distance to the accretion-powered millisecond pulsar SAX J1808.4-3658
• Fusion reactions in multicomponent dense matter
• Nucleosynthesis in Type I X-ray Bursts
• Thermonuclear X-ray bursts
• Possible Resonances in the 12C + 12C Fusion Rate and Superburst Ignition
• Nuclear Physics of the Outer Layers of Accreting Neutron Stars
• Sedimentation and Type I X-ray Bursts at Low Accretion Rates
• Accretion disks and coronae in the X-ray flashlight
• What ignites on the neutron star of 4U 0614+091?
• Microscopic sub-barrier fusion calculations for the neutron star crust
• Evidence of heavy-element ashes in thermonuclear X-ray bursts with photospheric superexpansion
• Phase separation in the crust of accreting neutron stars
• Observatory science with eXTP
• First superburst from a classical low-mass X-ray binary transient
• Nuclear Reactions in the Crusts of Accreting Neutron Stars
• A strong shallow heat source in the accreting neutron star MAXI J0556-332
• Deep Crustal Heating in a Multicomponent Accreted Neutron Star Crust
• Intermediate long X-ray bursts from the ultra-compact binary source SLX 1737-282
• Quiescent thermal emission from neutron stars in LMXBs
• Fusion of neutron rich oxygen isotopes in the crust of accreting neutron stars
• Influence of Nuclear Reaction Rate Uncertainties on Neutron Star Properties Extracted From X-ray Burst Model-Observation Comparisons
• Neutrino emission from triplet pairing of neutrons in neutron stars
• The effect of rotation on the stability of nuclear burning in accreting neutron stars
• Turbulent Mixing in the Surface Layers of Accreting Neutron Stars
• Multi-Zone Models of Superbursts from Accreting Neutron Stars
• Horizons: Nuclear Astrophysics in the 2020s and Beyond
• Achromatic late-time variability in thermonuclear X-ray bursts - an accretion disk disrupted by a nova-like shell?
• The Shear Viscosity and Thermal Conductivity of Nuclear Pasta
• X-ray Reflection and An Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143
• A direct measurement of the heat release in the outer crust of the transiently accreting neutron star XTE J1709-267
• Urca cooling pairs in the neutron star ocean and their effect on superbursts
• Evidence for crust cooling in the transiently accreting 11-Hz X-ray pulsar in the globular cluster Terzan 5
• Superfluid Response and the Neutrino Emissivity of Neutron Matter
• Radius-expansion burst spectra from 4U 1728-34: an ultracompact binary?
• Thermonuclear burst observations for model comparisons: a reference sample
• Constraining the properties of neutron star crusts with the transient low-mass X-ray binary Aql X-1
• The thermal state of KS 1731-260 after 14.5 years in quiescence
• Characterizing the Evolving X-Ray Spectral Features During a Superburst from 4U 1636-536
• Thermal conductivity and phase separation of the crust of accreting neutron stars
• Sequential deconfinement of quark flavors in neutron stars
• An X-ray and optical study of the ultracompact X-ray binary A1246-58
• Multi-epoch X-ray burst modelling: MCMC with large grids of 1D simulations
• Compositionally-driven convection in the oceans of accreting neutron stars
• Hydrogen-Triggered Type I X-ray Bursts in a Two-Zone Model
• Absence of hindrance in microscopic ${}^{12}$C+${}^{12}$C fusion study
• A superburst candidate in EXO 1745--248 as a challenge to thermonuclear ignition models
• Large collection of astrophysical S-factors and its compact representation
• Multi-wavelength observations of 1RXH J173523.7-354013: revealing an unusual bursting neutron star
• Long tails on thermonuclear X-ray bursts from neutron stars: a signature of inward heating?
• Consistent accretion-induced heating of the neutron-star crust in MXB 1659-29 during two different outbursts
• The cooling rate of neutron stars after thermonuclear shell flashes
• Carbon Detonation and Shock-Triggered Helium Burning in Neutron Star Superbursts
• IGR J17254-3257, a new bursting neutron star
• Searching for the most powerful thermonuclear X-ray bursts with the Neil Gehrels Swift Observatory
• Nuclear fusion reaction rates for strongly coupled ionic mixtures
• A catalogue of unusually long thermonuclear bursts on neutron stars
• The Swift capture of a long X-ray burst from XTE J1701-407
• The chemical composition of the accretion disk and donor star in Ultra Compact X-ray Binaries: A comprehensive X-ray analysis
• Deep crustal heating for realistic compositions of thermonuclear ashes
• Continued cooling of the accretion-heated neutron star crust in the X-ray transient IGR J17480-2446 located in the globular cluster Terzan 5
• Super-Eddington winds from Type I X-ray bursts
• The new intermediate long bursting source XTE J1701-407
• Carbon production on accreting neutron stars in a new regime of stable nuclear burning
• Time-dependent, compositionally driven convection in the oceans of accreting neutron stars
• Swift detection of an intermediately long X-ray burst from the very faint X-ray binary XMMU J174716.1-281048
• Multiwavelength characterisation of the accreting millisecond X-ray pulsar and ultra-compact binary IGR J17062-6143
• Effects of Nuclear Equation of State on Type-I X-ray Bursts: Interpretation of the X-ray Bursts from GS 1826-24
• Hydrodynamic Thermonuclear Runaways in Superbursts
• NICER views moderate, strong, and extreme photospheric expansion bursts from the ultracompact X-ray binary 4U 1820$-$30
• Carbon Synthesis in Steady-State Hydrogen and Helium Burning On Accreting Neutron Stars
• Superfluid response and the neutrino emissivity of baryon matter: Fermi-liquid effects
• Helium Ignition on Accreting Neutron Stars with a New Triple-alpha Reaction Rate
• The imprint of carbon combustion on a superburst from the accreting neutron star 4U 1636-536
• Maxi observations of long X-ray bursts
• An unusual precursor burst with oscillations from SAX J1808.4-3658
• Strong plasma screening in thermonuclear reactions: Electron drop model
• Relativistic outflow from two thermonuclear shell flashes on neutron stars
• The efficiency of nuclear burning during thermonuclear (Type I) bursts as a function of accretion rate
• Puzzling thermonuclear burst behaviour from the transient low-mass X-ray binary IGR J17473-2721
• Crust cooling of the neutron star in Aql X-1: Different depth and magnitude of shallow heating during similar accretion outbursts
• The Fermi-GBM 3-year X-ray Burst Catalog
• Impacts of the direct URCA and Superfluidity inside a Neutron Star on Type-I X-Ray Bursts and X-Ray Superbursts
• The Thermal Stability of Helium Burning on Accreting Neutron Stars
• Effects of a New Triple-alpha Reaction on X-ray Bursts of a Helium Accreting Neutron Star
• Discovery of transition from marginally stable burning to unstable burning after a superburst in Aql X-1
• The Influence of Stellar Spin on Ignition of Thermonuclear Runaways
• The Fermi-GBM X-ray burst monitor: thermonuclear bursts from 4U 0614+09
• Neutron degeneracy and plasma physics effects on radiative neutron captures in neutron star crust
• Burning in the tail: implications for a burst oscillation model
• Direct MD simulation of liquid-solid phase equilibria for two-component plasmas
• Astrophysics in 2006
• The Impacts of Neutron-Star Structure and Base Heating on Type I X-Ray Bursts and Code Comparison
• Ignition column depths of helium-rich thermonuclear bursts from 4U 1728-34
• Model of heat diffusion in the outer crust of bursting neutron stars
• Dynamics of Laterally Propagating Flames in X-ray Bursts. II. Realistic Burning & Rotation
• Novel Non-equilibrium Phase Transition Caused by Non-linear Hadronic-quark Phase Structure
• Deep crustal heating by neutrinos from the surface of accreting neutron stars
• On the ultra-compact nature of the neutron star system 1RXS J170854.4-321857: insights from X-ray spectroscopy
• Spin excitonic and diffusive modes in superfluid Fermi liquids
• Discovery of a long thermonuclear X-ray burst from the ultra-compact binary 4U 1850$-$087
• Quenching and recovery of persistent X-ray emission during a superburst in 4U 1820$-$30
• Theoretical exploration of $S$-factors for nuclear reactions of astrophysical importance
• Superfluid effects on gauging core temperatures of neutron stars in low-mass X-ray binaries
• The energetic thermonuclear bursts in SAX J1712.6-3739
• Study of the Hindrance Effect in Sub-barrier Fusion Reactions
• A catalog of intermediate duration Type I X-ray bursts observed with the INTEGRAL satellite
• Neutrino emission from Cooper pairs at finite temperatures
• Spallation-altered accreted compositions for X-ray bursts: Impact on ignition conditions and burst ashes
• Constraining Accreted Neutron Star Crust Shallow Heating with the Inferred Depth of Carbon Ignition in X-ray Superbursts
• Discovery of a strong 6.6 keV emission feature from EXO 1745$-$248 after the superburst in 2011 October
• Radiative neutron capture reaction rates for r-process nucleosynthesis
• Radiative neutron capture reaction rates for stellar nucleosynthesis
• Net reaction rate and neutrino emissivity for the Urca process in departure from chemical equilibrium
• NICER observations of type-I X-ray bursts from the ultra-compact X-ray binary M15 X-2
• Thermonuclear superburst of MAXI J1752$-$457 observed with NinjaSat and MAXI
• Connecting the m-dots: accretion rates and thermonuclear burst recurrence times on neutron stars and white dwarfs
• A new reduced network to simulate detonations in superbursts from mixed H/He accretors
• Long thermonuclear burst driven thermal-viscous instability of accretion disk: triggering an outburst-like X-ray flare
• A "Hyperburst" in the MAXI J0556-332 Neutron Star: Evidence for a New Type of Thermonuclear Explosion
• Tracing the outburst decay of soft X-ray transients Aql X-1 and 4U 1608-52 with XSPECT