Ядерна фізика та енергетика Nuclear Physics and Atomic Energy   ISSN: 1818-331X (Print), 2074-0565 (Online)   Publisher: Institute for Nuclear Research of the National Academy of Sciences of Ukraine   Languages: Ukrainian, English   Periodicity: 4 times per year   Open access peer reviewed journal

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A. A. Uleiev¹, A. G. Magner¹, S. P. Maydanyuk^2,3, A. Bonasera⁴, H. Zheng^5,*, S. N. Fedotkin¹, A. I. Levon⁶, U. V. Grygoriev¹, T. Depastas<sup>4

1</sup> Institute for Nuclear Research, National Academy of Sciences of Ukraine, Nuclear Theory Department, Kyiv, Ukraine
² Institute for Nuclear Research, National Academy of Sciences of Ukraine, Nuclear Processes Theory Department, Kyiv, Ukraine
³ Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
⁴ Cyclotron Institute, Texas A&M University, College Station, Texas, USA
⁵ School of Physics and Information Technology, Shaanxi Normal University, Xi'an, China
⁶ Institute for Nuclear Research, National Academy of Sciences of Ukraine, Heavy Ions Physics Department, Kyiv, Ukraine

^*Corresponding author. E-mail address: zhengh@snnu.edu.cn

Abstract: The macroscopic model for a neutron star (NS) as a perfect liquid drop at equilibrium is extended to rotating systems with a small frequency ω within the effective-surface (ES) approach. The gradient surface terms of the NS energy density ε(ρ) in the Equation of State are taken into account along with the volume components at the leading order over the leptodermic parameter, a/R << 1 where a is the ES crust thickness and R is the mean NS radius. The macroscopic NS angular momentum at small frequencies ω is used for calculations of the adiabatic moment of inertia (MI) within the Kerr metric approach in the outer Boyer - Lindquist and inner Hogan coordinate forms. The NS MI Θ=Θ̃/(1-G_tφ), was obtained in terms of the statistically averaged MI, Θ̃, and its time and azimuthal-angle correlation, G_tφ, as the sum of volume and surface components. The MI Θ depends dramatically on the effective radius R due to a strong gravitation and surface effects. We found significant additional rotational constraints on the radius R due to the correlation term G_tφ and surface contributions. With these contributions, the adiabaticity condition is better fulfilled for a stronger gravity in many well-known NSs.

Keywords: nuclear astrophysics, energy density, neutron star, Kerr metric, moments of inertia.

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