The Radius of PSR J0437-4715 from NICER Data

Abstract

Neutron star Interior Composition Explorer (NICER) data have been used to estimate the masses and radii of the rotation-powered millisecond pulsars PSR J0030$+$0451, PSR J0740$+$6620, PSR J0437$-$4715, PSR J1231$-$1411, and PSR J0614$-$3329, sometimes in joint analyses with X-ray Multi-Mirror (XMM-Newton) data. These measurements provide invaluable information about the properties of cold, catalyzed matter beyond nuclear saturation density. Here we present the results of our modeling of NICER data on PSR J0437$-$4715 using several different models of hot thermal X-ray emitting spots on the stellar surface. For this pulsar, previous Nuclear Spectroscopic Telescope Array (NuSTAR) observations established that there is also a modulated nonthermal component to the emission, but the previously published analysis of NICER data did not model this component. We find that the Bayesian evidence is significantly higher when the modulated nonthermal component is included, and that omission of this component leads to poor fits to the bolometric NICER data and thus risks bias in the resulting radius estimates. Our models, which we pursue to inferential convergence, therefore have modulated nonthermal emission, and our headline model has in addition three uniform-temperature thermally-emitting circular spots. Using this model, the symmetric 68% credible range in the radius is 11.8 km to 15.1 km, which at the independently-measured mass of $M=1.418\pm 0.044M_{\odot }$ is consistent with previous reports of the radius of the $\sim 1.4M_{\odot }$ pulsar PSR J0030$+$0451. We discuss the implications of this measurement for the equation of state of dense matter.

22 pages, 12 figures, submitted to The Astrophysical Journal Letters

References in corpus (52)

• Array Programming with NumPy
• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• PSR J0030+0451 Mass and Radius from NICER Data and Implications for the Properties of Neutron Star Matter
• A NICER View of PSR J0030+0451: Millisecond Pulsar Parameter Estimation
• A NICER View of the Massive Pulsar PSR J0740+6620 Informed by Radio Timing and XMM-Newton Spectroscopy
• Refined Mass and Geometric Measurements of the High-Mass PSR J0740+6620
• Constraining the Maximum Mass of Neutron Stars From Multi-Messenger Observations of GW170817
• PSR J0952-0607: The Fastest and Heaviest Known Galactic Neutron Star
• PolyChord: nested sampling for cosmology
• The NANOGrav 15-year Data Set: Observations and Timing of 68 Millisecond Pulsars
• Nonparametric constraints on neutron star matter with existing and upcoming gravitational wave and pulsar observations
• A NICER View of the Nearest and Brightest Millisecond Pulsar: PSR J0437$\unicode{x2013}$4715
• A statistical test for Nested Sampling algorithms
• An Empirical Background Model for the NICER X-ray Timing Instrument
• An updated mass-radius analysis of the 2017-2018 NICER data set of PSR J0030+0451
• Impact of the PSR J0740+6620 radius constraint on the properties of high-density matter
• Neutron star mass and radius measurements from atmospheric model fits to X-ray burst cooling tail spectra
• Spectral Representations of Neutron-Star Equations of State
• PINT: A Modern Software Package for Pulsar Timing
• The Radius of the High-mass Pulsar PSR J0740+6620 with 3.6 yr of NICER Data
• Chiral Effective Field Theory and the High-Density Nuclear Equation of State
• Constraining the Neutron Star Mass-Radius Relation and Dense Matter Equation of State with NICER. I. The Millisecond Pulsar X-ray Data Set
• Constraining the Neutron Star Mass-Radius Relation and Dense Matter Equation of State with NICER. II. Emission from Hot Spots on a Rapidly Rotating Neutron Star
• The Oblate Schwarzschild Approximation for Light Curves of Rapidly Rotating Neutron Stars
• Direct Astrophysical Tests of Chiral Effective Field Theory at Supranuclear Densities
• Ab-initio QCD calculations impact the inference of the neutron-star-matter equation of state
• The Radius of PSR J0740+6620 from NICER with NICER Background Estimates
• Nested Sampling Methods
• A model for the waveform behavior of accreting millisecond pulsars: Nearly aligned magnetic fields and moving emission regions
• Theoretical and Experimental Constraints for the Equation of State of Dense and Hot Matter
• A NICER View of PSR J1231$-$1411: A Complex Case
• Universality of the Acceleration Due to Gravity on the Surface of a Rapidly Rotating Neutron Star
• Accelerating astronomical and cosmological inference with Preconditioned Monte Carlo
• Constraining the dense matter equation-of-state with radio pulsars
• The neutron star mass, distance, and inclination from precision timing of the brilliant millisecond pulsar J0437$-$4715
• Constraining the Neutron Star Mass--Radius Relation and Dense Matter Equation of State with NICER. III. Model Description and Verification of Parameter Estimation Codes
• Phase Transition Phenomenology with Nonparametric Representations of the Neutron Star Equation of State
• A NICER view of the 1.4 solar-mass edge-on pulsar PSR J0614-3329
• Kilohertz quasiperiodic oscillations in short gamma-ray bursts
• Robust sampling for weak lensing and clustering analyses with the Dark Energy Survey
• Magnetospheric return-current-heated atmospheres of rotation-powered millisecond pulsars
• Atmospheric Structure and Radiation Pattern for Neutron-Star Polar Caps Heated by Magnetospheric Return Currents
• Cross-Comparison of Sampling Algorithms for Pulse Profile Modeling of PSR J0740+6620
• Notes on the Practical Application of Nested Sampling: MultiNest, (Non)convergence, and Rectification
• Assessing equation of state-independent relations for neutron stars with nonparametric models
• Exploring Waveform Variations among Neutron Star Ray-tracing Codes for Complex Emission Geometries
• Tight bound on neutron-star radius with quasiperiodic oscillations in short gamma-ray bursts
• Validating Sequential Monte Carlo for Gravitational-Wave Inference
• Gravitational Redshift for Rapidly Rotating Neutron Stars
• A Counterintuitive Correlation Between Neutron-Star Radii Inferred from Pulse Modeling and Surface Emission Beaming

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