32 research outputs found
Gravitational Shock Waves for Schwarzschild and Kerr Black Holes
The metrics of gravitational shock waves for a Schwarzschild black hole in
ordinary coordinates and for a Kerr black hole in Boyer-Lindquist coordinates
are derived. The Kerr metric is discussed for two cases: the case of a Kerr
black hole moving parallel to the rotational axis, and moving perpendicular to
the rotational axis. Then, two properties from the derived metrics are
investigated: the shift of a null coordinate and the refraction angle crossing
the gravitational shock wave. Astrophysical applications for these metrics are
discussed in short.Comment: 24 Pages, KOBE--FHD--93--03, {\LaTeX
A Note on the Symmetries of the Gravitational Field of a Massless Particle
It is shown that the metric of a massless particle obtained from boosting the
Schwarzschild metric to the velocity of light, has four Killing vectors
corresponding to an E(2)\times \RR symmetry-group. This is in agreement with
the expectations based on flat-space kinematics but is in contrast to previous
statements in the literature \cite{Schueck}. Moreover, it also goes beyond the
general Jordan-Ehlers-Kundt-(JEK)-classification of gravitational pp-waves as
given in \cite{JEK}.Comment: 10pages, amslatex, TUW-94-12 and UWThPh-1994-2
Nonlinear and Perturbative Evolution of Distorted Black Holes; 2, Odd-parity Modes
We compare the fully nonlinear and perturbative evolution of nonrotating black holes with odd-parity distortions utilizing the perturbative results to interpret the nonlinear results. This introduction of the second polarization (odd-parity) mode of the system, and the systematic use of combined techniques brings us closer to the goal of studying more complicated systems like distorted, rotating black holes, such as those formed in the final inspiral stage of two black holes. The nonlinear evolutions are performed with the 3D parallel code for Numerical Relativity, {Cactus}, and an independent axisymmetric code, {Magor}. The linearized calculation is performed in two ways: (a) We treat the system as a metric perturbation on Schwarzschild, using the Regge-Wheeler equation to obtain the waveforms produced. (b) We treat the system as a curvature perturbation of a Kerr black hole (but here restricted to the case of vanishing rotation parameter a) and evolve it with the Teukolsky equation The comparisons of the waveforms obtained show an excellent agreement in all cases