arXiv subjects
Publications and source records attributed to Janusz Karkowski.
A numerical procedure is described for the maximization of the energy diffusion due to the backscattering of the gravitational radiation. The obtained maxima are solutions dominated by low frequency waves. They give rise to robust gravitational ringing, with amplitudes of the order of the original signal.
Disturbing of a spacetime geometry may result in the appearance of an oscillating and damped radiation - the so-called quasinormal modes. Their periods of oscillations and damping coefficients carry unique information about the mass and the angular momentum, that would allow one to identify the source of the gravitational field. In this talk we present recent bounds on the diffused energy, applicable to the Schwarzschild spacetime, that give also rough estimates of the energy of excited quasinormal modes.
Major changes in Sec. II (with much stronger estimates), minor changes in remaining sections, a new title. Deleted Appendix, added 2 new references.
We investigate axially symmetric asymptotically flat vacuum self-gravitating system. A class of initial data with apparent horizon was numerically constructed. The examined solutions satisfy the Penrose inequality. The prior analysis of a massive system and the present results suggest that either massive or sourcefree configurations fulfill the Penrose inequality.