arXiv subjects

Frederick J. Ernst

Publications and source records attributed to Frederick J. Ernst.

4 recordsLinked to original sources

arXiv1994

Fully Electrified Neugebauer Spacetimes

Generalizing a method presented in an earlier paper, we express the complex potentials E and Phi of all stationary axisymmetric electrovac spacetimes that correspond to axis data of the form E(z,0) = (U-W)/(U+W) , Phi(z,0) = V/(U+W) , where U = z^{2} + U_{1} z + U_{2} , V = V_{1} z + V_{2} , W = W_{1} z + W_{2} , in terms of the complex parameters U_{1}, V_{1}, W_{1}, U_{2}, V_{2} and W_{2}, that are directly associated with the various multipole moments. (Revised to clarify certain subtle points.)

gr-qc↗

arXiv1994

Determining parameters of the Neugebauer family of vacuum spacetimes in terms of data specified on the symmetry axis

We express the complex potential E and the metrical fields omega and gamma of all stationary axisymmetric vacuum spacetimes that result from the application of two successive quadruple-Neugebauer (or two double-Harrison) transformations to Minkowski space in terms of data specified on the symmetry axis, which are in turn easily expressed in terms of multipole moments. Moreover, we suggest how, in future papers, we shall apply our approach to do the same thing for those vacuum solutions that arise from the application of more than two successive transformations, and for those electrovac solutions that have axis data similar to that of the vacuum solutions of the Neugebauer family. (References revised following response from referee.)

gr-qc↗

arXiv1993

Non-Analytic Extension of the Kinnersley-Chitre Group for Colliding Plane Gravitational Waves. I

A program is outlined concerning the set of all solutions of the hyperbolic Ernst equation on a two-dimensional manifold whose underlying topological space is the same as the domain of all Ernst potentials for colliding plane gravitational wave pairs. The aim of the program is to construct and apply a non-trivial extension of the group of Kinnersley-Chitre transformations. This is to be done by employing the formalism of a homogeneous Hilbert problem. In this first paper of a series, the aforementioned program is completely carried out for the collinear polarization case.

gr-qc↗

arXiv1993

Generalized Symmetries of the Einstein Equations

We reformulate the symmetries of Gurses [Phys. Rev. Lett. 70, 367 (1993)] in a more abstract, more geometrical manner. The type (b) transformation of \gurses\ is related to a diffeomorphism of the differentiable manifold onto itself. The type (c) symmetry is replaced by a more general type (c-bar) symmetry that has the nice property that the commutator of a type (c-bar) generator with a type (a) generator is itself of type (c-bar). We identify a differential constraint that transformations of type (c) and (c-bar) must satisfy, and which, in our opinion, may severely limit the usefulness of these transformations.

gr-qc↗