  We study the dynamics of a bounded gravitational collapsing configuration
emitting gravitational waves, where the exterior spacetime is described by
Robinson-Trautman geometries. The full nonlinear regime is examined by using
the Galerkin method that allows us to reduce the equations governing the
dynamics to a finite-dimensional dynamical system, after a proper truncation
procedure. Amongst the obtained results of the nonlinear evolution, one of the
most impressive is the fact that the distribution of the mass fraction
extracted by gravitational wave emission satisfies the distribution law of
nonextensive statistics and this result is independent of the initial
configurations considered.
