Revisiting Dynamical Friction: The Role of Global Modes and Local Wakes

The orbital decay of a perturber within a larger system plays a key role in the dynamics of many astrophysical systems-from nuclear star clusters or globular clusters in galaxies, to massive black holes in galactic nuclei, to dwarf galaxy satellites within the dark matter halos of more massive galaxies. For many decades, there have been various attempts to determine the underlying physics and timescales of the drag mechanism, ranging from the local dynamical friction approach to descriptions based on the back-reaction of global modes induced in the background system. We present ultra-high-resolution N-body simulations of massive satellites orbiting a Milky Way-like galaxy (with > 10(8) particles), that appear to capture both the local wake and the global mode induced in the primary halo. We address directly the mechanism of orbital decay from the combined action of local and global perturbations and specifically analyze where the bulk of the torque originates.

Automated summary

The text discusses the orbital decay of a perturber within a larger system and the attempts to determine the underlying physics and timescales of the drag mechanism using different approaches. Through ultra-high-resolution N-body simulations, both local and global perturbations' effects were captured and the torque's origin was analyzed.