## Séminaire de Physique Théorique

**Computing black hole horizons geometry and dynamics**

Nicolas Vasset (LUTH, Paris)

Thursday 29 April 2010 14:00 - Tours - Salle 1180 (Bât E2)

**Résumé :**

We present numerical studies aiming at the computation of black hole spacetimes using a model for horizon geometry, in the context of a fully constrained (3+1) formalism in numerical relativity. Based on the quasi-local notions of isolated horizons and dynamical horizons, we try to compute such structures via a boundary condition problem for Einstein equations, allowing us to construct the whole excised spacetime. This approach has the asset of allowing in general precise computations in the near zone of the black hole region. We show that a particular feature of Einstein equations (in Dirac gauge) on a single isolated horizon leads to a derivation of the conformal metric in a stationary spacetime, that does not require any information at the boundary. In the fully dynamical case, we present a method for computing the formation and evolution of a single black hole in a general spacetime using the notion of effective dynamical horizons. This method is designed to be used in core collapse simulations for computing precisely the dynamics of the inner region of collapsars post black hole formation.

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