Effective N-body models of composite collisionless stellar systems

Gas-poor galaxies can be modelled as composite collisionless stellar systems, with a dark matter halo and one or more stellar components, representing different stellar populations. The dynamical evolution of such composite systems is often studied with numerical N-body simulations, whose initial conditions typically require realizations with particles of stationary galaxy models. We present a novel method to conceive these N-body realizations, which allows one to exploit at best a collisionless N-body simulation that follows their evolution. The method is based on the use of an effective N-body model of a composite system, which is in fact realized as a one-component system of particles that is interpreted a posteriori as a multicomponent system, by assigning in post-processing fractions of each particle's mass to different components. Examples of astrophysical applications are N-body simulations that aim to reproduce the observed properties of interacting galaxies, satellite galaxies, and stellar streams. As a case study we apply our method to an N-body simulation of tidal stripping of a two-component (dark matter and stars) satellite dwarf galaxy orbiting in the gravitational potential of the Milky Way.

Automated summary

Gas-poor galaxies can be modeled as composite collisionless stellar systems and studied using numerical N-body simulations. A novel method is presented to conceive N-body realizations, where each particle's mass is assigned fractions to different components for post-processing. This method is applied to an N-body simulation of tidal stripping of a two-component satellite dwarf galaxy orbiting the Milky Way.