A Counterintuitive Correlation Between Neutron-Star Radii Inferred from Pulse Modeling and Surface Emission Beaming
arXiv:2412.12284 · doi:10.3847/1538-4357/adb9ea
Abstract
Thermal X-ray emission from rotation-powered millisecond pulsars, shaped by gravitational lensing and the beaming of the surface radiation, provides critical insights into neutron star properties. This approach has been the focus of observations with the NICER mission. Using a semi-analytic model to calculate pulse profiles, we investigate the effects of adopting incorrect beaming models on the inferred compactness of neutron stars. We demonstrate that assuming a more centrally peaked beaming pattern when fitting data from a more isotropic emitter leads to an underestimation of compactness in the case of two antipodal polar caps. We present a detailed analysis of this counterintuitive result, offering both qualitative insights and quantitative estimates. If the atmospheric heating in the millisecond pulsars observed with NICER is shallow, the inferred radii for these sources could be significantly overestimated, with important implications for neutron star structure and equation-of-state constraints.
arXiv commentSubmitted to the Astrophysical Journal
References in corpus (19)
- 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
- The Cooling of Compact Stars
- Gravitational Bending of Light Near Compact Objects
- A NICER View of the Nearest and Brightest Millisecond Pulsar: PSR J0437$\unicode{x2013}$4715
- An updated mass-radius analysis of the 2017-2018 NICER data set of PSR J0030+0451
- 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
- Pulse profiles of millisecond pulsars and their Fourier amplitudes
- Surface Emission from Neutron Stars and Implications for the Physics of their Interiors
- Model Atmospheres for Low Field Neutron Stars
- Determining neutron star masses and radii using energy-resolved waveforms of X-ray burst oscillations
- Determining Neutron Star Properties by Fitting Oblate-Star Waveforms To X-ray Burst Oscillations
- X-ray Lightcurves from Realistic Polar Cap Models: Inclined Pulsar Magnetospheres and Multipole Fields
- Atmospheric Effects on Neutron Star Parameter Constraints with NICER
- 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
- Optimized Statistical Approach for Comparing Multi-Messenger Neutron Star Data