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Speaker |
Kotrlová, Andrea |
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Co-autors |
Zdenek Stuchlik |
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Talk Title |
Orbital resonance models of QPOs in braneworld Kerr black holes |
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Abstract |
Rotating black holes in the brany universe of the Randall-Sundrum type with infinite additional dimension are described by the Kerr geometry with a tidal charge $b$ representing the interaction of the brany black hole and the bulk spacetime. For $b<0$ rotating black holes with dimensionless spin $a>1$ are allowed. We investigate the role of the tidal charge in the orbital resonance model of quasiperiodic oscillations (QPOs) in black hole systems. The orbital Keplerian frequency and the radial and vertical epicyclic frequencies of the equatorial, quasicircular geodetical motion are given and their radial profiles are discussed. We show how the tidal charge could influence matching of the observational data indicating the 3:2 frequency ratio observed in GRS 1915+105 and GRO J1655-40 microquasars with prediction of the orbital resonance model; limits on allowed range of the black hole parameters $a$ and $b$ are established. The "magic" dimensionless black hole spin enabling presence of strong resonant phenomena at the radius where $\nu_K:\nu_\theta:\nu_r = 3:2:1$ is determined in dependence on the tidal charge. Such strong resonances could be relevant even in sources with highly scattered resonant frequencies, as those expected in Sgr A*. We can conclude that analysing the microquasars high-frequency QPOs in the framework of orbital resonance models, we can put relevant limits on the tidal charge of brany Kerr black holes. |
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