Influence of self-gravity on the runaway instability of black hole-torus systems

TL;DR

This study uses general relativistic simulations to investigate how the self-gravity of a torus affects the runaway instability in black hole-torus systems, finding that self-gravity does not significantly promote the instability in early times.

Contribution

First fully relativistic axisymmetric simulations showing that torus self-gravity does not trigger runaway instability during initial dynamical times.

Findings

Self-gravity does not induce runaway instability early on

Tori exhibit stable oscillations without instability

Self-gravity's role is limited in initial phases

Abstract

Results from the first fully general relativistic numerical simulations in axisymmetry of a system formed by a black hole surrounded by a self-gravitating torus in equilibrium are presented, aiming to assess the influence of the torus self-gravity on the onset of the runaway instability. We consider several models with varying torus-to-black hole mass ratio and angular momentum distribution orbiting in equilibrium around a non-rotating black hole. The tori are perturbed to induce the mass transfer towards the black hole. Our numerical simulations show that all models exhibit a persistent phase of axisymmetric oscillations around their equilibria for several dynamical timescales without the appearance of the runaway instability, indicating that the self-gravity of the torus does not play a critical role favoring the onset of the instability, at least during the first few dynamical timescales.