Chaotic Loss Cones, Black Hole Fueling and the M-Sigma Relation

TL;DR

This paper investigates how non-axisymmetric, triaxial galactic nuclei can significantly increase stellar feeding rates to central black holes, potentially explaining the observed M-sigma relation and resolving the final parsec problem.

Contribution

It evaluates stellar capture rates in triaxial nuclei, showing they surpass classical models and can account for the M-sigma relation and black hole binary evolution.

Findings

Feeding rates in triaxial nuclei exceed classical loss cone predictions.

Captured mass scales as the fifth power of velocity dispersion.

Triaxiality helps solve the final parsec problem.

Abstract

In classical loss cone theory, stars are supplied to a central black hole via gravitational scattering onto low angular momentum orbits. Higher feeding rates are possible if the gravitational potential near the black hole is non-axisymmetric and the orbits are chaotic. Motivated by recently published, self-consistent models, we evaluate rates of stellar capture and disruption in triaxial nuclei. Rates are found to substantially exceed those in collisionally-resupplied loss cones, as long as an appreciable fraction of the orbits are centrophilic. The mass captured by a black hole after a given time in a steep nucleus scales as the fifth power of the velocity dispersion, and the accumulated mass in 10^10 yr is of the correct order to reproduce the M-sigma relation. Triaxiality can solve the "final parsec problem" of decaying black hole binaries by increasing the flux of stars into the binary's loss cone.