Frozen Neutron Stars in Four-Dimensional Non-polynomial Gravities

Fuente: arXiv
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Main Authors: Tan, Chen, Wang, Yong-Qiang
Format: Preprint
Published: 2025
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author Tan, Chen
Wang, Yong-Qiang
author_facet Tan, Chen
Wang, Yong-Qiang
contents This paper investigates the structure and properties of neutron stars in four-dimensional non-polynomial gravities. Solving the modified Tolman-Oppenheimer-Volkoff equations for three different equations of state (BSk19, SLy4, AP4), we confirm that neutron star solutions remain in existence. As the modification parameter $α$ increases, neutron stars grow in both radius and mass. We find that, when the parameter $α$ is sufficiently large, a frozen state emerges at the end of the neutron-star sequence. In this state, the metric functions approach zero extremely close to the stellar surface, forming a critical horizon, making it nearly indistinguishable from a black hole to an external observer. Such a frozen neutron star constitutes a universal endpoint of the neutron-star sequence in this theory, independent of the choice of the equation of state. Based on our results and current observational constraints, we derive bounds on the modification parameter $α$ and show that frozen neutron stars remain allowed in the bounds.
format Preprint
id arxiv_https___arxiv_org_abs_2512_23525
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Frozen Neutron Stars in Four-Dimensional Non-polynomial Gravities
Tan, Chen
Wang, Yong-Qiang
General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
High Energy Physics - Theory
This paper investigates the structure and properties of neutron stars in four-dimensional non-polynomial gravities. Solving the modified Tolman-Oppenheimer-Volkoff equations for three different equations of state (BSk19, SLy4, AP4), we confirm that neutron star solutions remain in existence. As the modification parameter $α$ increases, neutron stars grow in both radius and mass. We find that, when the parameter $α$ is sufficiently large, a frozen state emerges at the end of the neutron-star sequence. In this state, the metric functions approach zero extremely close to the stellar surface, forming a critical horizon, making it nearly indistinguishable from a black hole to an external observer. Such a frozen neutron star constitutes a universal endpoint of the neutron-star sequence in this theory, independent of the choice of the equation of state. Based on our results and current observational constraints, we derive bounds on the modification parameter $α$ and show that frozen neutron stars remain allowed in the bounds.
title Frozen Neutron Stars in Four-Dimensional Non-polynomial Gravities
topic General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
High Energy Physics - Theory
url https://arxiv.org/abs/2512.23525