A NICER View of PSR J0030+0451: Updated Constraints from Six Years of NICER Observations

Yves Kini; Lucien Mauviard; Tuomo Salmi; Anna L. Watts; Sebastien Guillot; Bas Dorsman; Devarshi Choudhury; Denis González-Caniulef; Mariska Hoogkamer; Daniela Huppenkothen; Christine Kazantsev; Matthew Kerr; Samaya Nissanke; Paul S. Ray; Pierre Stammler; Serena Vinciguerra

arXiv · 2602.23743

A NICER View of PSR J0030+0451: Updated Constraints from Six Years of NICER Observations

Yves Kini·Lucien Mauviard·Tuomo Salmi·Anna L. Watts·Sebastien Guillot·Bas Dorsman·Devarshi Choudhury·Denis González-Caniulef·Mariska Hoogkamer·Daniela Huppenkothen·Christine Kazantsev·Matthew Kerr·Samaya Nissanke·Paul S. Ray·Pierre Stammler·Serena Vinciguerra

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Abstract

Pulse-profile modeling of rotation-powered millisecond pulsars targeted by NICER has enabled mass--radius constraints of several neutron star sources, with implications for the dense-matter equation of state. For the bright isolated pulsar PSR J0030+0451, the inferred mass--radius was previously found to depend strongly on the assumed hot spot model. These hot-spot models yielded different mass--radius constraints, with the statistically preferred model exhibiting some mild tension with results inferred for PSR J0437$-$4715, PSR~J0614$-$3329, and GW170817. We present an updated pulse-profile analysis of PSR J0030+0451 using new NICER observations obtained between 2017 July to 2023 January, increasing the number of X-ray counts by about 50% compared to previous analyses. We jointly analyze the NICER data with archival XMM-Newton observations to better constrain the source spectrum and background. The new analysis significantly reduces the discrepancy between the hot spot models. The inferred mass and radius are $M = 1.43^{+0.20}_{-0.17}\,M_\odot$ and $R_{\rm eq} = 12.68^{+1.31}_{-1.04}$ km (68% credible intervals), reducing the tension with the results from other sources. In addition, the inferred hot spot configurations suggest the presence of intra-spot temperature gradients.

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Yves Kini, Lucien Mauviard, Tuomo Salmi, Anna L. Watts, Sebastien Guillot, Bas Dorsman, Devarshi Choudhury, Denis González-Caniulef, Mariska Hoogkamer, Daniela Huppenkothen, Christine Kazantsev, Matthew Kerr, Samaya Nissanke, Paul S. Ray, Pierre Stammler, Serena Vinciguerra. 2026-02-27. A NICER View of PSR J0030+0451: Updated Constraints from Six Years of NICER Observations. https://arxiv.org/abs/2602.23743

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