Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Abstract
We report Bayesian inference of the mass, radius, and hot X-ray emitting region properties—using data from the Neutron Star Interior Composition ExploreR (NICER)—for the brightest rotation-powered millisecond X-ray pulsar, PSR J0437−4715. Our modeling is conditional on informative tight priors on mass, distance, and binary inclination obtained from radio pulsar timing using the Parkes Pulsar Timing Array (PPTA Reardon et al.), and we use NICER background models to constrain the nonsource background, cross-checking with data from XMM-Newton. We assume two distinct hot emitting regions and various parameterized hot region geometries that are defined in terms of overlapping circles while simplified, these capture many of the possibilities suggested by detailed modeling of return current heating. For the preferred model identified by our analysis, we infer a mass of M = 1.418 ± 0.037 M ⊙ (largely informed by the PPTA mass prior) and an equatorial radius of R = 11.36 − 0.63 + 0.95 km, each reported as the posterior credible interval bounded by the 16% and 84% quantiles. This radius favors softer dense matter equations of state and is highly consistent with constraints derived from gravitational wave measurements of neutron star binary mergers. The hot regions are inferred to be nonantipodal and hence inconsistent with a pure centered dipole magnetic field.
Department
Physics
Publication Date
8-1-2024
Journal Title
The Astrophysical Journal Letters
Publisher
American Astronomical Society
Digital Object Identifier (DOI)
Document Type
Article
Recommended Citation
Devarshi Choudhury et al 2024 ApJL 971 L20 DOI 10.3847/2041-8213/ad5a6f
Rights
© 2024. The Author(s).
Comments
This is an open access article published by American Astronomical Society in The Astrophysical Journal Letters in 2024, available online: https://dx.doi.org/10.3847/2041-8213/ad5a6f