SÉMINAIRE DU GRECO
" Causal nature and dynamics of trapping horizons in black hole collapse and cosmology " 

I. Musco 

In calculations of gravitational collapse to form black holes, trapping horizons (foliated by marginally trapped surfaces) make their first appearance either within the collapsing matter or where it joins on to a vacuum exterior. Those which then move outwards with respect to the matter have been proposed for use in defining black holes, replacing the global concept of an ``event horizon" which has some serious drawbacks for practical applications. We focus here on studying the properties of trapping horizons within spherical symmetry (which gives some simplifications while retaining the most essential general features). Their locations are then given by exactly the same condition ($R=2M$) as for the event horizon in the vacuum Schwarzschild metric, and the same condition also applies for cosmological trapping horizons. We have investigated the causal nature of these horizons (i.e.\ whether they are spacelike, timelike or null), making contact with the MisnerSharp


lundi 21 mars 2016  11:00 Salle des séminaires Évry Schatzman, Institut d'Astrophysique de Paris 
