paper

A Full Loss Cone For Triaxial Galaxies

arXiv:astro-ph/0601520

Abstract

Stars and compact objects that plunge toward a black hole are either 1) captured, emitting gravitational waves as the orbit decays, 2) tidally disrupted, leaving a disc of baryonic material, 3) scattered to a large radius, where they may thereafter avoid encounters with the black hole or 4) swallowed whole, contributing to black hole growth. These processes occur on a dynamical time, which implies that for a static spherically symmetric stellar system, the loss cone is quickly emptied. However, most elliptical galaxies and spiral bulges are thought to be triaxial in shape. The centrophilic orbits comprising the backbone of a triaxial galaxy have been suggested as one way to keep the loss cone around a supermassive black hole filled with stars, stellar remnants, and intermediate mass black holes. We investigate the evolution of the loss cone population in a triaxial galaxy model with high resolution N-body simulations. We find that enough regular orbits flow through angular momentum space to maintain a full loss cone for a Hubble time. This increases the astrophysical capture rate by several orders of magnitude. In the Milky Way, for example, we find that the white dwarf capture rate can be as high as per year, 100 times larger than previous estimates based on spherical models for the bulge.

arXiv comment22 pages, 6 figures, submitted to MNRAS

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