New constraints on the nuclear equation of state from the thermal emission of neutron stars in quiescent low-mass X-ray binaries

Abstract

This paper presents a new analysis of the thermal emission from the neutron star surface to constrain the dense matter equation of state. It is based on the use of a Markov-Chain Monte Carlo algorithm combined with an empirical parametrization of the equation of state, as well as the consistent treatment of seven neutron star quiescent low-mass X-ray binaries in globular clusters with well-measured distances. Previous analyses have indicated that the thermal emission of these neutron stars tends to prefer low neutron star radii, questioning basic knowledge from nuclear physics. We show that it is possible to reconcile the thermal emission analyses with nuclear physics knowledge, with or without including a prior on the slope of the symmetry energy $L_{\mathrm{sym}}$. We obtain radii of the order of about 12~km without worsening the fit statistic. With an empirical parametrization of the equation of state, we obtain the following values for the slope of the symmetry energy, its curvature $K_{\mathrm{sym}}$, and the isoscalar skewness parameter $Q_{\mathrm{sat}}$: $L_{\mathrm{sym}}=37.2_{-8.9}^{+9.2}$ MeV, $K_{\mathrm{sym}}=-85_{-70}^{+82}$ MeV, and $Q_{\mathrm{sat}}=318_{-366}^{+673}$ MeV. For the first time, we measure the values of the empirical parameters $K_{\mathrm{sym}}$ and $Q_{\mathrm{sat}}$. These values are only weakly impacted by our assumptions, such as the distances or the number of free empirical parameters, provided they are taken within a reasonable range. We also study the weak sensitivity of our results to the set of sources analyzed, and we identify a group of sources that dominates the constraints. The resulting masses and radii obtained are also discussed in the context of the independent constraints from GW 170817 and its electromagnetic counterpart, AT 2017gfo.

arXiv commentAccepted for publication in The Astrophysical Journal

References in corpus (76)

• emcee: The MCMC Hammer
• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• The Gaia mission
• On the Absorption of X-rays in the Interstellar Medium
• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• GW170817: Measurements of Neutron Star Radii and Equation of State
• Neutron Star Observations: Prognosis for Equation of State Constraints
• Masses, Radii, and Equation of State of Neutron Stars
• A unified equation of state of dense matter and neutron star structure
• Constraining neutron star tidal Love numbers with gravitational wave detectors
• Gravitational-wave constraints on the neutron-star-matter Equation of State
• Constraints on a phenomenologically parameterized neutron-star equation of state
• Equation of state and neutron star properties constrained by nuclear physics and observation
• The NANOGrav Nine-year Data Set: Mass and Geometric Measurements of Binary Millisecond Pulsars
• Tidal Deformabilities and Radii of Neutron Stars from the Observation of GW170817
• The NANOGrav 11-year Data Set: High-precision timing of 45 Millisecond Pulsars
• GW170817: Joint Constraint on the Neutron Star Equation of State from Multimessenger Observations
• Neutron-star radius constraints from GW170817 and future detections
• Constraining the Symmetry Parameters of the Nuclear Interaction
• The Neutron Star Mass-Radius Relation and the Equation of State of Dense Matter
• Astrophysical Measurement of the Equation of State of Neutron Star Matter
• The Dense Matter Equation of State from Neutron Star Radius and Mass Measurements
• Constraining the Equation of State with Moment of Inertia Measurements
• Constraining the speed of sound inside neutron stars with chiral effective field theory interactions and observations
• Crustal Heating and Quiescent Emission from Transiently Accreting Neutron Stars
• A critical examination of constraints on the equation of state of dense matter obtained from GW170817
• A Hydrogen Atmosphere Spectral Model Applied to the Neutron Star X7 in the Globular Cluster 47 Tucanae
• A Neutron Star with a Carbon Atmosphere in the Cassiopeia A Supernova Remnant
• The equation of state for dense nucleonic matter from a metamodeling. I. Foundational aspects
• Pulsar J0453+1559: A Double Neutron Star System with a Large Mass Asymmetry
• Neutron Star Masses and Radii from Quiescent Low-Mass X-ray Binaries
• Towards a Mass and Radius Determination of the Nearby Isolated Neutron Star RX J185635-3754
• Constraining the Mass and Radius of Neutron Stars in Globular Clusters
• Tidal deformability from GW170817 as a direct probe of the neutron star radius
• Measurement of the Radius of Neutron Stars with High S/N Quiescent Low-mass X-ray Binaries in Globular Clusters
• Neutron star stiff equation of state derived from cooling phases of the X-ray burster 4U 1724-307
• Neutron star mass and radius measurements from atmospheric model fits to X-ray burst cooling tail spectra
• Models of crustal heating in accreting neutron stars
• The equation of state for dense nucleonic matter from a meta-modeling. II. Predictions for neutron stars properties
• The thermal radiation of the isolated neutron star RX J1856.5-3754 observed with Chandra and XMM-Newton
• The Thermal X-ray Spectra of Cen X-4, Aql X-1, and 4U 1608-522 in Quiescence
• Improved Mass and Radius Constraints for Quiescent Neutron Stars in Omega Cen and NGC 6397
• The Oblate Schwarzschild Approximation for Light Curves of Rapidly Rotating Neutron Stars
• The Nearest Millisecond Pulsar Revisited with XMM-Newton: Improved Mass-Radius Constraints for PSR J0437-4715
• Variable Thermal Emission from Aql X-1 in Quiescence
• Equation of state constraints for the cold dense matter inside neutron stars using the cooling tail method
• Constraints on Neutron Star Properties from X-ray Observations of Millisecond Pulsars
• The millisecond pulsar mass distribution: Evidence for bimodality and constraints on the maximum neutron star mass
• Rejecting proposed dense-matter equations of state with quiescent low-mass X-ray binaries
• Neutron Star Mass-Radius Constraints of the Quiescent Low-mass X-ray Binaries X7 and X5 in the Globular Cluster 47 Tuc
• Constraining the equation of state of supra-nuclear dense matter from XMM-Newton observations of neutron stars in globular clusters
• The mass and the radius of the neutron star in the transient low mass X-ray binary SAX J1748.9-2021
• Relations Between Neutron-Star Parameters in the Hartle-Thorne Approximation
• From Neutron Star Observables to the Equation of State. I. An Optimal Parametrization
• Discrete dynamical modelling of omega Centauri
• Systematic Uncertainties in the Spectroscopic Measurements of Neutron-Star Masses and Radii from Thermonuclear X-ray Bursts. I. Apparent Radii
• The neutron star in HESS J1731-347: CCOs as laboratories to study the equation of state of superdense matter
• The influence of accretion geometry on the spectral evolution during thermonuclear (type-I) X-ray bursts
• On the compactness of the isolated neutron star RX J0720.4-3125
• The variable quiescence of Cen X-4
• Neutron Star Radius Measurement with the Quiescent Low-Mass X-ray Binary U24 in NGC 6397
• Evolution of Young Neutron Star Envelopes
• Absolute Ages and Distances of 22 GCs using Monte Carlo Main-Sequence Fitting
• Distances to the globular clusters 47 Tucanae and NGC 362 using Gaia DR2 parallaxes
• Neutron star atmosphere composition: the quiescent, low-mass X-ray binary in the globular cluster M28
• Diffusive Nuclear Burning of Helium on Neutron Stars
• A Homogenous Set of Globular Cluster Relative Distances and Reddenings
• Systematic Uncertainties in the Spectroscopic Measurements of Neutron-Star Masses and Radii from Thermonuclear X-ray Bursts. II. Eddington Limit
• Globular clusters with Gaia
• HST/ACS Imaging of Omega Centauri: Optical Counterpart for the Quiescent Low-Mass X-Ray Binary
• The radius of the quiescent neutron star in the globular cluster M13
• Mass/Radius Constraints on the Quiescent Neutron Star in M13 Using Hydrogen and Helium Atmospheres
• Detection of a Quiescent Low Mass X-Ray Binary Companion in 47 Tucanae
• Constraints on physics of neutron stars from X-ray observations

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