Effective N-body models of composite collisionless stellar systems

TL;DR

This paper introduces a novel method for creating initial conditions for N-body simulations of composite collisionless stellar systems, enabling more accurate modeling of galaxy interactions and evolution.

Contribution

The paper presents a new approach to generate N-body realizations of composite systems as single-component models, interpreted as multi-component post-processing, improving simulation efficiency and accuracy.

Findings

Method successfully applied to simulate tidal stripping of a dwarf galaxy.

Allows post-processing interpretation of single-component models as multi-component systems.

Enhances modeling of galaxy interactions and stellar streams.

Abstract

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 multi-component 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.