Detection of the gravitomagnetic clock effect

The essence of the gravitomagnetic clock effect is properly defined showing that its origin is in the topology of world lines with closed space projections. It is shown that, in weak field approximation and for a spherically symmetric central body, the loss of synchrony between two clocks counter-rotating along a circular geodesic is proportional to the angular momentum of the source of the gravitational field. Numerical estimates are presented for objects within the solar system. The less unfavorable situation is found around Jupiter.Comment: 14 pages; Latex. To be published on Classical and Quantum Gravit

Comment on the new AdS universe

We show that Bonnor's new Anti-de Sitter (AdS) universe and its D-dimensional generalization is the previously studied AdS soliton.Comment: 2 pages; version 2: major changes including the titl

Equivalence of Darmois-Israel and Distributional-Methods for Thin Shells in General Relativity

A distributional method to solve the Einstein's field equations for thin shells is formulated. The familiar field equations and jump conditions of Darmois-Israel formalism are derived. A carefull analysis of the Bianchi identities shows that, for cases under consideration, they make sense as distributions and lead to jump conditions of Darmois-Israel formalism.Comment: 17 pages Latex, no figures, to be published in Journ. Math. Phy

Electromagnetic radiation produces frame dragging

It is shown that for a generic electrovacuum spacetime, electromagnetic radiation produces vorticity of worldlines of observers in a Bondi--Sachs frame. Such an effect (and the ensuing gyroscope precession with respect to the lattice) which is a reminiscence of generation of vorticity by gravitational radiation, may be linked to the nonvanishing of components of the Poynting and the super--Poynting vectors on the planes othogonal to the vorticity vector. The possible observational relevance of such an effect is commented.Comment: 8 pages RevTex 4-1; updated version to appear in Physical Review

Colliding axisymmetric pp-waves

An exact solution is found describing the collision of axisymmetric pp-waves with M=0. They are impulsive in character and their coordinate singularities become point curvature singularities at the boundaries of the interaction region. The solution is conformally flat. Concrete examples are given, involving an ultrarelativistic black hole against a burst of pure radiation or two colliding beam- like waves.Comment: 6 pages, REVTeX, some misprints are correcte

Regular and quasi black hole solutions for spherically symmetric charged dust distributions in the Einstein-Maxwell theory

Static spherically symmetric distributions of electrically counterpoised dust (ECD) are used to construct solutions to Einstein-Maxwell equations in Majumdar--Papapetrou formalism. Unexpected bifurcating behaviour of solutions with regard to source strength is found for localized, as well as for the delta-function ECD distributions. Unified treatment of general ECD distributions is accomplished and it is shown that for certain source strengths one class of regular solutions approaches Minkowski spacetime, while the other comes arbitrarily close to black hole solutions.Comment: LaTeX (IOP style) 17 pages, 10 figure