Equation of state and neutron star properties with new mass-radius constraints from PSR~J1614--2230, PSR~J2124--3358, and 47~Tuc~X7

Melissa Mendes; Isak Svensson; Hannah Gottling; Kai Hebeler; Achim Schwenk; Nathan Rutherford; Lucien Mauviard; Christine Kazantsev; Yves Kini; Denis Gonzalez-Caniulef; Sebastien Guillot; Anna Watts

arXiv · 2609.00173

Equation of state and neutron star properties with new mass-radius constraints from PSR~J1614--2230, PSR~J2124--3358, and 47~Tuc~X7

Melissa Mendes·Isak Svensson·Hannah Gottling·Kai Hebeler·Achim Schwenk·Nathan Rutherford·Lucien Mauviard·Christine Kazantsev·Yves Kini·Denis Gonzalez-Caniulef·Sebastien Guillot·Anna Watts

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Abstract

We study the impact of new mass-radius information from PSR J1614-2230, PSR J2124-3358, and 47 Tuc X7 in a combined equation of state inference based on chiral effective field theory constraints at nuclear densities and using different high-density extensions, including perturbative QCD constraints. The largest impact stems from the heavy-mass PSR J1614-2230 star, which shifts heavy neutron stars to smaller radii by around 0.4 km. Moreover, the combined astrophysical NICER, LIGO/Virgo, and X-ray information drives the radius posterior to a more data-driven distribution, which is less sensitive to the high-density extension. For the equation of state, the new mass-radius information significantly tightens the pressure and speed-of-sound posterior distributions, especially around three times saturation density. Finally, we make predictions for the poorly constrained masses of PSR J2124-3358 and 47 Tuc X7 based on the combined equation of state analysis and the other astrophysical sources.

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Melissa Mendes, Isak Svensson, Hannah Gottling, Kai Hebeler, Achim Schwenk, Nathan Rutherford, Lucien Mauviard, Christine Kazantsev, Yves Kini, Denis Gonzalez-Caniulef, Sebastien Guillot, Anna Watts. 2026-08-31. Equation of state and neutron star properties with new mass-radius constraints from PSR~J1614--2230, PSR~J2124--3358, and 47~Tuc~X7. https://arxiv.org/abs/2609.00173

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