MG12 - Talk detail
 

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Abstract

Mass and spin estimates of two near-extreme Kerr black hole candidates GRS 1915+105 and XTE J1650-500 from the Extended Orbital Resonance Model for high-frequency QPOs

Humpy profile of the LNRF-related orbital velocity was found for accretion discs orbiting rapidly rotating Kerr black holes with a spin a>0.9953. The positive rate of change of the orbital velocity in terms of the proper radial distance is used to define a local frequency in the disc. Comparing the "humpy frequency" with epicyclic frequencies of the orbital motion, it was shown that in Keplerian discs orbiting specific near-extreme Kerr black holes (a>0.998) the radial epicyclic frequency and the humpy frequency are in the ratio of small integers. The model was applied to two X-ray variable sources. In the case of GRS 1915+105, the model is able to address the whole set of reported QPOs, giving the mass and spin of the black hole: a=0.9998, M=14.8M_sun. For XTE J1650-500, similar ideas give values a=0.9982, M=5.1M_sun.

Pseudo-Newtonian modelling of adiabatic tori in Schwarzschild–de Sitter spacetimes

Pseudo-Newtonian gravitational potential for spherically symmetric black-hole spacetimes with a repulsive cosmological constant is applied to equilibrium toroidal configurations of barotropic perfect fluid orbiting black holes. Shapes and potential depths are determined for the marginally stable barotropic tori with uniform distribution of the specific angular momentum. For the adiabatic (isoentropic) perfect fluid, temperature profiles, mass-density and pressure profiles are presented and total masses are calculated. All results are compared with exact general relativistic ones.

Pseudo-Newtonian modelling of adiabatic tori in Schwarzschild–de Sitter spacetimes

Pseudo-Newtonian gravitational potential for spherically symmetric black-hole spacetimes with a repulsive cosmological constant is applied to equilibrium toroidal configurations of barotropic perfect fluid orbiting black holes. Shapes and potential depths are determined for the marginally stable barotropic tori with uniform distribution of the specific angular momentum. For the adiabatic (isoentropic) perfect fluid, temperature profiles, mass-density and pressure profiles are presented and total masses are calculated. All results are compared with exact general relativistic ones.

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