Comparison of the Hartle-Thorne Model of Neutron Stars with its Kerr Approximation by using Resonant Switch Model

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F47813059%3A19630%2F21%3AA0000171" target="_blank" >RIV/47813059:19630/21:A0000171 - isvavai.cz</a>

Result on the web

<a href="http://acta.astrouw.edu.pl/Vol71/n4/a_71_4_4.html" target="_blank" >http://acta.astrouw.edu.pl/Vol71/n4/a_71_4_4.html</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.32023/0001-5237/71.4.4" target="_blank" >10.32023/0001-5237/71.4.4</a>

Result language

angličtina

Original language name

Comparison of the Hartle-Thorne Model of Neutron Stars with its Kerr Approximation by using Resonant Switch Model

Original language description

The Hartle-Thorne (H-T) models of slowly rotating neutron or quark stars, characterized by the mass M, dimensionless spin a, and reduced quadrupole moment q, are constructed for the observationally given rotational frequency frot = 580 Hz (290 Hz) of the compact star in the atoll source 4U 1636-53, and a wide range of equations of state (EoS) giving sequences of allowed states governed by the relations a(M), q(M). These sequences are used in the framework of the resonant switch (RS) model combining pairs of geodesic oscillation models to match the data of the twin high-frequency quasi-periodic oscillations observed in the 4U 1636-53 source. The results of the matching procedure using the H-T models are compared to those based on the Kerr approximation of the exterior of the neutron stars. The best H-T matches fix the only variant of the RS model combining particular modifications of the relativistic precession model, exclude the rotation frequency frot = 290 Hz, restrict the considered EoS to six of them, excluding the strange quark stars, and significantly improve precision of the matches given by any single geodesic oscillations model. The Kerr matching allows two variants of the RS model, thus, giving false information, and only three EoS, thus, giving insufficient information. Our results demonstrate that in the matching procedure, the Kerr approximation can be used only for neutron stars governed by the H-T models with q &lt; 2, implying an important restriction on the applicability of the Kerr approximation for description of the oscillatory phenomena around neutron stars. On the other hand, the RS model is sufficiently discriminating for the spacetime metric to be largely determined by fitting to the data. The ranges of the external spacetime parameters of the neutron stars related to the best H-T matches are determined to be M approximate to 2.10-2.13 M-circle dot , a approximate to 0.21-0.25, q approximate to 1.8-2.3. Most compact neutron star is predicted by the Gandolfi EoS, when M approximate to 2.10 M-circle dot , a approximate to 0.21, q approximate to 1.8, with the equatorial radius R approximate to 10.83 km and eccentricity epsilon = 0.03.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

<a href="/en/project/LTT17003" target="_blank" >LTT17003: Investigation of baryonic systems at FAIR international research facility</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>S - Specificky vyzkum na vysokych skolach<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2021

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Acta Astronomica

ISSN

0001-5237

e-ISSN

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Volume of the periodical

71

Issue of the periodical within the volume

4

Country of publishing house

PL - POLAND

Number of pages

31

Pages from-to

311-341

UT code for WoS article

000751812700004

EID of the result in the Scopus database

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