The authors study the radial motion along null geodesics in the Reissner-Nordström-de Sitter and Kerr-de Sitter space-times. They analyze the properties of the effective potential and discuss circular orbits. They find that the radii of circular geodesics in the Reissner-Nordström-de Sitter space-time do not depend on the cosmological constant, and explain this property using the optical reference geometry. In addition, the authors describe the unusual consequences of the interplay between rotation of the source and cosmological repulsion.
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The authors study the radial motion along null geodesics in the
Reissner-Nordström-de Sitter and Kerr-de Sitter space-times. They
analyze the properties of the effective potential and discuss circular
orbits. They find that the radii of circular geodesics in the
Reissner-Nordström-de Sitter space-time do not depend on the
cosmological constant, and explain this property using the optical
reference geometry. In addition, the authors describe the unusual
consequences of the interplay between rotation of the source and
cosmological repulsion.
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The motion in the equatorial plane is discussed in three cases which exhibit well the interaction of charged particles and Kerr-Newman black holes. These are: (1) the circular orbits of ultrarelativistic particles with high specific charge; (2) the motion of charged particles with zero angular momentum (where the interplay between the gravitational and magnetic dragging can be seen in the simplest form); and (3) the motion of charged particles with l = a x gamma (including all particles that can hit the ring singularity and also the cases when the trajectories can be given in terms of elementary functions).
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The motion in the equatorial plane is discussed in three cases which
exhibit well the interaction of charged particles and Kerr-Newman black
holes. These are: (1) the circular orbits of ultrarelativistic particles
with high specific charge; (2) the motion of charged particles with zero
angular momentum (where the interplay between the gravitational and
magnetic dragging can be seen in the simplest form); and (3) the motion
of charged particles with l = a x gamma (including all particles that
can hit the ring singularity and also the cases when the trajectories
can be given in terms of elementary functions).
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The general characteristics of the motion of charged test particles in a field of rotating charged black holes and naked singularities are discussed. The general features of radial motion and motion along the axis of symmetry are studied, using the method of effective potentials. The differences between charged particle motion in the field of Kerr-Newman sources and uncharged particle motion in Kerr spacetime are examined.
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A fully general relativistic nonlinear model of the formation of massive
neutrino halos in an Einstein-Straus universe was given by Fabbri,
Jantzen and Ruffini (1982). The paper considers the role which a
nonvanishing, repulsive cosmological constant Lambda greater than 0,
admissible by observational limits, can have in the FJR model. The main
conclusion is that the influence of Lambda is negligible in the FJR
model for massive neutrinos with mass of about 10 eV, indicated by
recent observations of SN 1987a. On the other hand, the cosmological
constant is relevant in the model, if neutrinos have low mass, less than
0.2 eV.
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A fully general relativistic non-linear model of the formation of massive neutrino halos in an Einstein-Straus universe was given by Fabbri, Jantzen and Ruffini. Here the author considers the role which a non-vanishing, repulsive cosmological constant Λ > 0, admissible by observational limits, can have in the FJR model.
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The possibility of constructing an Einstein-Strauss-de Sitter model of the Universe (i.e. a model of Schwarzschild-de Sitter mass condensations immersed in a Friedmann universe with the cosmological constant Λ present) is proved. Geodesic motion is considered in both the Schwarzschild-de Sitter and Friedmann parts of the model, and the matching of geodesics across the matching hypersurface of these parts is given. Some consequences of this geodesics-matching, which should be relevant in the process of formation and evolution of mass condensations due to gravitational instability of massive neutrinos in a neutrino-dominated universe, are discussed.
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The possibility of constructing an Einstein-Strauss-de Sitter model of
the Universe (i.e. a model of Schwarzschild-de Sitter mass condensations
immersed in a Friedmann universe with the cosmological constant Λ
present) is proved. Geodesic motion is considered in both the
Schwarzschild-de Sitter and Friedmann parts of the model, and the
matching of geodesics across the matching hypersurface of these parts is
given. Some consequences of this geodesics-matching, which should be
relevant in the process of formation and evolution of mass condensations
due to gravitational instability of massive neutrinos in a
neutrino-dominated universe, are discussed.
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We investigate the role of the cosmological constant in the formation of neutrino halos. Using the observational limit λ≦10-55 cm-2 we find that it is relevant only for neutrinos of very light rest-mass: namely, ≦10-1 eV.
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