Numerical Relativity Simulations of the Papaloizou-Pringle Instability in Black Hole-Torus Systems

Astrophysical systems composed by a black hole surrounded by a thick accretion disk (or torus) are the most promising candidates to account for the central engine of gamma-ray bursts, both resulting from the (failed) collapse of a massive star or from the merger of a compact binary system formed by two neutron stars or by a black hole and a neutron star. Such systems are also possibly formed following the collapse of supermassive stars to supermassive black holes. We present here three-dimensional general relativistic numerical simulations of such systems and show that an m = 1 non-axisymmetric instability grows for a wide range of self-gravitating tori orbiting black holes. The long-lived asymmetry present in the torus turns it into a significant source of large amplitude, quasiperiodic gravitational waves, potentially detectable by forthcoming ground-based and spacecraft detectors.