Accuracy and Applicability of the Hartle-Thorne and Komatsu-Eriguchi-Hachisu Methods for Modeling Rotating Neutron Stars

Fuente: arXiv
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Main Authors: Kwon, Hyukjin, Yoshimura, Kenta, Miyatsu, Tsuyoshi, Sekizawa, Kazuyuki, Cheoun, Myung-Ki
Format: Preprint
Published: 2025
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author Kwon, Hyukjin
Yoshimura, Kenta
Miyatsu, Tsuyoshi
Sekizawa, Kazuyuki
Cheoun, Myung-Ki
author_facet Kwon, Hyukjin
Yoshimura, Kenta
Miyatsu, Tsuyoshi
Sekizawa, Kazuyuki
Cheoun, Myung-Ki
contents Neutron stars, which are composed of extremely dense nuclear matter, serve as natural laboratories to study nuclear interactions beyond the terrestrial experiments. Recent researches have actively explored how the equation of state (EoS) can be constrained by observed neutron star masses and radii, and how nuclear interactions affect their macroscopic properties. Most of these studies, however, rely on the Tolman-Oppenheimer-Volkoff (TOV) equations, which assumed static, spherically symmetric neutron stars. Since neutron stars are rotating objects and thus axisymmetrically deformed, the TOV calculation may be insufficient to capture their realistic structure. In this work, we investigate the influence of nuclear matter properties on the physical quantities of rotating neutron stars using two approaches: the perturbative Hartle-Thorne (HT) method and fully general relativistic Komatsu-Eriguchi-Hachisu (KEH) method. For nuclear EoS parameter sets, we emamine the OMEG series, in which the slope of the symmetry energy $L$ is systematically varied. We find that rotational effects lead to a noticeable increase in the stellar radius, which depends sensitively on values of $L$. Additionally, focusing on the rotational deformation, we show that the results obtained by these two methods deviate each other even for the slowly rotating case such as $Ω=200$ Hz. These results reveal that, for detailed discussions on the internal structure and stability of rotating neutron stars, the fully general relativistic method such as KEH is indispensable.
format Preprint
id arxiv_https___arxiv_org_abs_2511_10996
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Accuracy and Applicability of the Hartle-Thorne and Komatsu-Eriguchi-Hachisu Methods for Modeling Rotating Neutron Stars
Kwon, Hyukjin
Yoshimura, Kenta
Miyatsu, Tsuyoshi
Sekizawa, Kazuyuki
Cheoun, Myung-Ki
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
General Relativity and Quantum Cosmology
Nuclear Theory
Neutron stars, which are composed of extremely dense nuclear matter, serve as natural laboratories to study nuclear interactions beyond the terrestrial experiments. Recent researches have actively explored how the equation of state (EoS) can be constrained by observed neutron star masses and radii, and how nuclear interactions affect their macroscopic properties. Most of these studies, however, rely on the Tolman-Oppenheimer-Volkoff (TOV) equations, which assumed static, spherically symmetric neutron stars. Since neutron stars are rotating objects and thus axisymmetrically deformed, the TOV calculation may be insufficient to capture their realistic structure. In this work, we investigate the influence of nuclear matter properties on the physical quantities of rotating neutron stars using two approaches: the perturbative Hartle-Thorne (HT) method and fully general relativistic Komatsu-Eriguchi-Hachisu (KEH) method. For nuclear EoS parameter sets, we emamine the OMEG series, in which the slope of the symmetry energy $L$ is systematically varied. We find that rotational effects lead to a noticeable increase in the stellar radius, which depends sensitively on values of $L$. Additionally, focusing on the rotational deformation, we show that the results obtained by these two methods deviate each other even for the slowly rotating case such as $Ω=200$ Hz. These results reveal that, for detailed discussions on the internal structure and stability of rotating neutron stars, the fully general relativistic method such as KEH is indispensable.
title Accuracy and Applicability of the Hartle-Thorne and Komatsu-Eriguchi-Hachisu Methods for Modeling Rotating Neutron Stars
topic High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
General Relativity and Quantum Cosmology
Nuclear Theory
url https://arxiv.org/abs/2511.10996