Influence of Cosmological Constant on Physics near Black Holes
Jiri Kovar
(Silesian University, Opava, Czech Republic)
Coauthor(s): Zdenek Stuchlik, Petr Slany
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Data from a wide variety of independent cosmological tests indicate that more than 70% of energy content of the Universe is in the form of so-called `dark energy', which can be well represented by the repulsive cosmological constant in Einstein's equations. It is well known that cosmological constant strongly influences expansion of the Universe, leading finally to an accelerated stage. In our work, we have studied possible effects of cosmological constant in astrophysically motivated problems, investigating properties of test-particle motion, spinning test-particle motion and perfect fluid configuration in black-hole Schwarzschild-de Sitter solution of Einstein's equations and in black-hole and naked-singularity Kerr-de Sitter solutions. In order to emphasise the influence of the cosmological constant, we have compared our results with the related ones when cosmological constant is zero. All the mentioned problems have been presented in terms of the standard general relativistic approaches, such as Carter's equations, effective potential, Papapetrou equation of motion, general relativistic Euler equation, etc. The test-particle and fluid properties have been treated also in the framework of the optical reference geometry allowing introduction of inertial forces in the intuitive natural Newtonian way. Investigating a circular motion, just this approach seems to be more convenient in comparison with the standard general relativistic ones. Moreover, we have shown that in some particular cases in the Schwarzschild-de Sitter spacetimes, especially in the test particle motion and adiabatic perfect fluid tori investigations, it is possible to employ even the pseudo-Newtonian approach, based on appropriately chosen gravitational potential within the Newtonian physics. The differences between the pseudo-Newtonian and general-relativistic results can be considered as negligible in most of the investigated problems, such as determination of the marginally bound and stable circular orbits, shapes, masses, central densities, temperatures and pressures of the adiabatic tori.