Epicyclic Oscillations in the Hartle-Thorne External Geometry

@article{37362,
   author = {Urbancová, Gabriela and Urbanec, Martin and Török, Gabriel and Stuchlík, Zdeněk and Blaschke, Martin and Miller, John},
   article_number = {2},
   doi = {http://dx.doi.org/10.3847/1538-4357/ab1b4c},
   keywords = {stars: oscillations; stars: neutron; stars: rotation; X-rays: binaries},
   language = {eng},
   issn = {0004-637X},
   journal = {Astrophysical Journal},
   title = {Epicyclic Oscillations in the Hartle-Thorne External Geometry},
   url = {https://iopscience.iop.org/article/10.3847/1538-4357/ab1b4c},
   volume = {877},
   year = {2019}
}

TY  - JOUR
ID  - 37362
AU  - Urbancová, Gabriela - Urbanec, Martin - Török, Gabriel - Stuchlík, Zdeněk - Blaschke, Martin - Miller, John
PY  - 2019
TI  - Epicyclic Oscillations in the Hartle-Thorne External Geometry
JF  - Astrophysical Journal
VL  - 877
IS  - 2
SP  - "66-1"-"66-17"
EP  - "66-1"-"66-17"
SN  - 0004637X
KW  - stars: oscillations
KW  - stars: neutron
KW  - stars: rotation
KW  - X-rays: binaries
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/ab1b4c
L2  - https://iopscience.iop.org/article/10.3847/1538-4357/ab1b4c
N2  - The external Hartle-Thorne geometry, which describes the spacetime outside a slowly rotating compact star, is characterized by the gravitational mass M, angular momentum J, and quadrupole moment Q of the star and gives a convenient description, which, for the rotation frequencies of more than 95% of known pulsars, is sufficiently accurate for most purposes. We focus here on the motion of particles in these spacetimes, presenting a detailed systematic analysis of the frequency properties of radial and vertical epicyclic motion and of orbital motion. Our investigation is motivated by X-ray observations of binary systems containing a rotating neutron star that is accreting matter from its binary companion. In these systems, twin high-frequency quasi-periodic oscillations (QPOs) are sometimes observed with a frequency ratio approaching 3:2 or 5:4, and these may be explained by models involving the orbital and epicyclic frequencies of quasi-circular geodesic motion. In our analysis, we use realistic equations of state for the stellar matter and proceed in a self-consistent way, following the Hartle-Thorne approach in calculating both the corresponding values of Q, M, and J for the stellar model and the properties of the surrounding spacetime. Our results are then applied to a range of geodetical models for QPOs. A key feature of our study is that it implements the recently discovered universal relations among neutron-star parameters so that the results can be directly used for models with different masses M, radii R, and rotational frequencies f_(rot).
ER  - 

URBANCOVÁ, Gabriela, Martin URBANEC, Gabriel TÖRÖK, Zdeněk STUCHLÍK, Martin BLASCHKE and John MILLER. Epicyclic Oscillations in the Hartle-Thorne External Geometry. \textit{Astrophysical Journal}. 2019, vol.~877, No~2, p.~''66-1''-''66-17'', 17 pp. ISSN~0004-637X. Available from: https://dx.doi.org/10.3847/1538-4357/ab1b4c.