Departament d'Astronomia i Astrofísica
Universitat de València

    Self-gravitating Tori around black holes and their instabilities

Nikolaos Stergioulas

Aristotle University of Thessaloniki, Grècia

Seminari del departament d'Astronomia i Astrofísica

Dimecres 22 febrer 2012



We give an overview of recent progress in constructing equilibrium models of self-gravitating tori around black holes, using a self-consistent field method. We focus on the properties of models with constant specific angular momentum that exactly fill their Roche lobe and show that their angular momentum is limited in the same way as in the case of a fixed background metric. Furthermore, we explore the stability of such disks against runaway and nonaxisymmetric instabilities using three-dimensional hydrodynamics simulations in full general relativity. All of our models develop unstable nonaxisymmetric modes on a dynamical time scale.We observe two distinct types of instabilities: the Papaloizou-Pringle and the so-called intermediate type instabilities. The development of the nonaxisymmetric mode with azimuthal number m=1 is accompanied by an outspiraling motion of the black hole, which significantly amplifies the growth rate of the m=1 mode in some cases. We comment on the generation of gravitational waves and on the development of the runaway instability