The Radius of PSR J0437-4715 from NICER Data

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Main Authors: Miller, M. C., Dittmann, A. J., Holt, I. M., Lamb, F. K., Chirenti, C., Arzoumanian, Z., Berteaud, J., Bogdanov, S., Gendreau, K. C., Ho, W. C. G., Morsink, S. M., Ray, P. S., Remillard, R. A., Wadiasingh, Z., Wolff, M. T.
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Published: 2025
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author Miller, M. C.
Dittmann, A. J.
Holt, I. M.
Lamb, F. K.
Chirenti, C.
Arzoumanian, Z.
Berteaud, J.
Bogdanov, S.
Gendreau, K. C.
Ho, W. C. G.
Morsink, S. M.
Ray, P. S.
Remillard, R. A.
Wadiasingh, Z.
Wolff, M. T.
author_facet Miller, M. C.
Dittmann, A. J.
Holt, I. M.
Lamb, F. K.
Chirenti, C.
Arzoumanian, Z.
Berteaud, J.
Bogdanov, S.
Gendreau, K. C.
Ho, W. C. G.
Morsink, S. M.
Ray, P. S.
Remillard, R. A.
Wadiasingh, Z.
Wolff, M. T.
contents 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 $M=1.418\pm 0.044~M_\odot$ is consistent with previous reports of the radius of the $\sim 1.4~M_\odot$ pulsar PSR J0030$+$0451. We discuss the implications of this measurement for the equation of state of dense matter.
format Preprint
id arxiv_https___arxiv_org_abs_2512_08790
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Radius of PSR J0437-4715 from NICER Data
Miller, M. C.
Dittmann, A. J.
Holt, I. M.
Lamb, F. K.
Chirenti, C.
Arzoumanian, Z.
Berteaud, J.
Bogdanov, S.
Gendreau, K. C.
Ho, W. C. G.
Morsink, S. M.
Ray, P. S.
Remillard, R. A.
Wadiasingh, Z.
Wolff, M. T.
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
Nuclear Theory
Neutron star Interior Composition Explorer (NICER) data have been used to estimate the masses and radii of the rotation-powered millisecond pulsars PSR J0030$+$0451, PSR J0740$+$6620, PSR J0437$-$4715, PSR J1231$-$1411, and PSR J0614$-$3329, sometimes in joint analyses with X-ray Multi-Mirror (XMM-Newton) data. These measurements provide invaluable information about the properties of cold, catalyzed matter beyond nuclear saturation density. Here we present the results of our modeling of NICER data on PSR J0437$-$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 $M=1.418\pm 0.044~M_\odot$ is consistent with previous reports of the radius of the $\sim 1.4~M_\odot$ pulsar PSR J0030$+$0451. We discuss the implications of this measurement for the equation of state of dense matter.
title The Radius of PSR J0437-4715 from NICER Data
topic High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
Nuclear Theory
url https://arxiv.org/abs/2512.08790