APT1 - Observations of Astrophysical Black Holes |
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Speaker |
Kotrlová, Andrea |
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Co-autors |
Zdenek Stuchlik, Gabriel Torok, Karel Adamek |
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Talk Title |
Multi-resonance models of QPOs and black holes admitting strong resonanant phenomena |
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Abstract |
Using known frequencies of the accretion disc twin peak quasiperiodic oscillations (QPOs) and the known mass of the central black hole, the black hole dimensionless spin $a$ can be determined, assuming a concrete version of the orbital resonance model. Higher precision of the black hole spin measurement is possible in the framework of multi-resonance model of QPOs inspired by complex high-frequency QPO patterns observed in some black hole and neutron star systems. We give the epicyclic frequencies with influence of $\Lambda>0$ taking into account. In the multi-resonant model, the twin peak resonances are combined properly to give the observed frequency set. The multi-resonant model is proposed in three distinct versions. In the first one, related probably to the neutron star binary systems, more instances of one resonance occur at more specific radii. In the second case, more resonances are sharing one specific radius, allowing for „cooperative“ strong resonant phenomena in the field of black holes with a specific („magic“) value of spin. In the third („ugly“) case, more resonances occur at more specific radii; we restrict our attention to the case of two such resonant radii. For special values of the spin, only triple-set of frequencies is observed because of coincidence of some frequencies, allowing determination of the spin from the triple frequency ratio set. The spin is determined precisely, but not uniquely as the same frequency set could be relevant for more than one concrete spin and combination of resonant oscillations. |
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Talk view |
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