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"Rotating stars and wave extraction: applications of curvature invariants in astrophysical relativity."

Relatore: Prof. Marco Bruni- Institute of Cosmology and Gravitation, University of Portsmouth,England (UK)

Sala Feynman
14 Dicembre 2004 ore 15.30

Weyl scalars appear as curvature variables in the Newman-Penrose formalism, and are traditionally used in exact solutions studies. The main application outside this context is in the Teukolsky formalism for the study of perturbations of Kerr rotating black holes. In this talk I will illustrate how the use of Weyl scalars, and of curvature invariants constructed from them, turn out to be useful in two other applications, both of relevance for the study of sources of gravitational radiation. The first is a study of relativistic rotating stars. In this context we want to assess the validity of the Hartle-Thorne slow-rotation approximation, comparing with full-GR numerical models, and to measure the deviation of the spacetime from Petrov type D, in view of the possible construction of a Teukolsky-like formalism for the study of perturbations of rotating stars. The second is the study of the problem of "wave extraction" in numerical relativity, i.e. the problem of invariantly identifying the radiation signal contained in relativistic simulations of gravitational wave sources