Oscillations of fluid tori around neutron stars

0574435 - ASÚ 2024 RIV US eng J - Journal Article
Šrámková, E. - Matuszková, J. - Klimovičová, K. - Horák, Jiří - Straub, O. - Urbancová, G. - Urbanec, M. - Karas, Vladimír - Török, G. - Lančová, D.
Oscillations of fluid tori around neutron stars.
Astronomische Nachrichten. Roč. 344, č. 1-2 (2023), č. článku e20220114. ISSN 0004-6337. E-ISSN 1521-3994
R&D Projects: GA ČR(CZ) GX21-06825X; GA MŠMT LTI17018
Institutional support: RVO:67985815
Keywords : accretion disks * dense matter * equation of state
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 0.9, year: 2022
Method of publishing: Limited access
https://doi.org/10.1002/asna.20220114

We examine the influence of quadrupole moment of a slowly rotating neutron star (NS) on the oscillations of a fluid accretion disk (torus) orbiting a compact object the spacetime around which is described by the Hartle-Thorne geometry. Explicit formulae for non-geodesic orbital epicyclic and precession frequencies, as well as their simplified practical versions that allow for an expeditious application of the universal relations determining the NS properties, are obtained and examined. We demonstrate that the difference in the accretion disk precession frequencies for NSs of the same mass and angular momentum, but different oblateness, can reach up to tens of percent. Even higher differences can arise when NSs with the same mass and rotational frequency, but different equations of state (EoS), are considered. In particular, the Lense-Thirring precession frequency defined in the innermost parts of the accretion region can differ by more than one order of magnitude across NSs with different EoS. Our results have clear implications for models of the LMXBs variability.
Permanent Link: https://hdl.handle.net/11104/0345951