Podrobný výpis o publikaci

Resonant Switch (RS) model of twin peak high-frequency quasi-periodic oscillations (HF QPOs) assumes switch of twin oscillations at a resonant point where frequencies of the upper and lower oscillations VU and V L become commensurable and the twin oscillations change from one pair of the oscillating modes (corresponding to a specific model of HF QPOs) to some other pair due to nonlinear resonant phenomena. The RS model is used to determine range of allowed values of spin a and mass M of the neutron starlocated in the atoll source 4U 1636-53 where two resonant points are observed at frequency ratios VU: VL = 3:2,5:4. We consider the standard specific models of the twin oscillations based on the orbital and epicyclic geodetical frequencies. The resonantpoints are determined by the energy switch effect exhibited by the vanishing of the amplitude difference of the upper and lower oscillations. The predicted ranges of the neutron star parameters are strongly dependent on the twin modes ap