Podrobný výpis o publikaci

We study frequencies of axisymmetric and non-axisymmetric epicyclic modes of accretion disk oscillations and explore the influence of pressure forces present in the disk. We utilize both approximate analytic methods and methods dealing with exact numerical solutions. Our investigation implies consequences for estimations of black hole spin in the three Galactic microquasars, namely GRS 1915+105, GRO J1655-40, and XTE J1550-564, which have been carried out based on several models of 3:2 high-frequency quasiperiodic oscillations (QPOs). In the particular case of 3:2 epicyclic resonance model, the presence of pressure forces affects the predicted QPO frequencies only slightly when a < 0.9. On the contrary, when a > 0.9, the influence of pressure forces is nonnegligible. Our findings indicate that for several models this influence can be quite significant even for low values of spin.