Perturbations of stars and black holes have been one of the main topics of relativistic astrophysics for the last few decades. They are of particular importance today, because of their relevance to… (More)

We show that the (4 + 1)-dimensional vacuum Einstein equations admit gravitational waves with radial symmetry. The dynamical degrees of freedom correspond to deformations of the three-sphere… (More)

Relativistic elasticity on an arbitrary spacetime is formulated as a Lagrangian field theory which is covariant under spacetime diffeomorphisms. This theory is the relativistic version of classical… (More)

It is shown that some known solutions of Einstein’s vacuum field equations admit null infinities such that the sections of the null hypersurface at infinity are toroidal. PACS numbers: 0420G, 0420H,… (More)

We propose a new, augmented formulation of the coupled Euler-Einstein equations for perfect fluids on plane-symmetric Gowdy spacetimes. The unknowns of the augmented system are the density and… (More)

We prove that given a stress-free elastic body there exists, for sufficiently small values of the gravitational constant, a unique static solution of the Einstein equations coupled to the equations… (More)

The asymptotic behavior of Einstein-Rosen waves at null infinity in 4 dimensions is investigated in all directions by exploiting the relation between the 4-dimensional space-time and the… (More)

Within a scalar model theory of gravity, where the interaction between particles is given by the half-retarded plus half-advanced solution of the scalar wave equation, we consider an N-body problem:… (More)