Talk detail

Participant	Stuchlik, Zdenek
Institution	Silesian University in Opava - Bezrucovo nam. 13 - Opava - Moravian-Silesian Region - Czech Republic

Session	AC1	Accepted		Order	Time
Talk	Oral abstract	Title	High-frequency quasiperiodic oscillations in accretion disks orbiting black holes and neutron stars
Coauthors
Abstract	High-frequency qusiperiodic oscillations (HF QPOs) observed in accretion structures around black holes and neutron stars in X-ray spectra of low-mass binary systems bring important information on the strong gravity processes. In the case of twin HF QPOs with rational frequency ratios observed in microquasars (systems containing black holes), they can be successfully modelled by the so-called geodesic multi-resonance models enabling an efficient estimation of the black hole parameters. We demonstrate that the multi-resonance models could be very efficient in explanation of the variable twin HF QPOs observed in some atoll sources containing neutron stars with external field described by the Hartle-Thorne geometry (or even by the Kerr approximation for high-mass neutron stars). We show that extension of the multi-resonance model gives interesting predictions for supermassive black holes in active galactic nuclei.
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Session	BH2	Accepted		Order	Time
Talk	Oral abstract	Title	Shadows of Kerr Black Holes and Kerr Superspinars
Coauthors
Abstract	One of the most important signatures of the presence of Kerr black holes or their alternatives represented by Kerr superspinars with exterior governed by the Kerr naked singularity geometry are their shadows occurring on the radiating background represented by an accretion disk. We demonstrate qualitative differences between the black-hole and superspinar shadows enabling their immediate distinction. Since the shadows are governed by the spherical photon orbits, we discuss properties of the spherical photons and their possible influence on the accretion disks.
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