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@article{59504,
author = {Stuchlík, Zdeněk and Klimovičová, Kateřina and Schee, Jan and Török, Gabriel and Kotrlová, Andrea},
article_location = {PL - Polská republika},
article_number = {4},
doi = {http://dx.doi.org/10.32023/0001-5237/71.4.4},
keywords = {Stars: neutron;Stars: oscillations;Equation of state;X-rays: binaries},
language = {eng},
issn = {0001-5237},
journal = {Acta Astronomica},
title = {Comparison of the Hartle-Thorne Model of Neutron Stars with its Kerr Approximation by using Resonant Switch Model},
url = {http://acta.astrouw.edu.pl/Vol71/n4/a_71_4_4.html},
volume = {71},
year = {2021}
}
TY - JOUR
ID - 59504
AU - Stuchlík, Zdeněk - Klimovičová, Kateřina - Schee, Jan - Török, Gabriel - Kotrlová, Andrea
PY - 2021
TI - Comparison of the Hartle-Thorne Model of Neutron Stars with its Kerr Approximation by using Resonant Switch Model
JF - Acta Astronomica
VL - 71
IS - 4
SP - 311-341
EP - 311-341
SN - 00015237
KW - Stars: neutron;Stars: oscillations;Equation of state;X-rays: binaries
UR - http://acta.astrouw.edu.pl/Vol71/n4/a_71_4_4.html
N2 - 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 < 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.
ER -
STUCHLÍK, Zdeněk, Kateřina KLIMOVIČOVÁ, Jan SCHEE, Gabriel TÖRÖK and Andrea KOTRLOVÁ. Comparison of the Hartle-Thorne Model of Neutron Stars with its Kerr Approximation by using Resonant Switch Model. \textit{Acta Astronomica}. PL - Polská republika, 2021, vol.~71, No~4, p.~311-341. ISSN~0001-5237. Available from: https://dx.doi.org/10.32023/0001-5237/71.4.4.
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