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"3D collapse to Kerr black holes: dynamics of matter, trapped surfaces and gravitational radiation and Beyond."

Relatore: Luca Baiotti- SISSA, Trieste
Note: Cambio di Orario

Sala Feynman
12 Ottobre 2004 ore

We present a new three-dimensional fully general relativistic hydrodynamics code using high-resolution shock-capturing techniques and a conformal traceless formulation of the Einstein equations. We discuss its application to the study of the gravitational collapse of uniformly rotating neutron stars to Kerr black holes. The initial stellar models are modelled as relativistic polytropes which are either secularly or dynamically unstable and with angular velocities which range from slow rotation to the mass-shedding limit. We investigate the gravitational collapse by carefully studying not only the dynamics of the matter, but also that of the trapped surfaces, {it i.e.} of both the apparent and event horizons formed during the collapse. The ability to successfully perform these simulations for sufficiently long times relies on excising a region of the computational domain which includes the singularity and is within the apparent horizon. We also present the first calculation of gravitational-wave emission produced in the gravitational collapse of uniformly rotating neutron to Kerr black holes in fully three-dimensional simulations. An essential aspect of these simulations is the use of progressive mesh-refinement techniques which allow to move the outer boundaries of the computational domain to regions where gravitational radiation attains its asymptotic form. The waveforms have been extracted using a gauge-invariant approach in which the numerical spacetime is matched with the non-spherical perturbations of a Schwarzschild spacetime. Most of our simulations are performed on the Albert100 cluster in Parma.