Dynamical friction and scratches of orbiting satellite galaxies on host systems

TL;DR

This paper uses high-resolution N-body simulations and an analytical model to study how orbiting satellite galaxies induce density wakes and dynamical responses in their host systems, confirming predictions with real galaxy pairs.

Contribution

It introduces a new analytical model predicting host density responses, including traditional and mirror-image wakes, verified by high-resolution simulations.

Findings

Confirmed the existence of mirror-image density features.

Validated the analytical model with billion-particle simulations.

Applied model predictions to real galaxy systems like Milky Way-LMC.

Abstract

We study the dynamical response of extended systems, hosts, to smaller systems, satellites, orbiting around the hosts using extremely high-resolution N-body simulations with up to one billion particles. This situation corresponds to minor mergers which are ubiquitous in the scenario of hierarchical structure formation in the universe. According to Chandrasekhar (1943), satellites create density wakes along the orbit and the wakes cause a deceleration force on satellites, i.e. dynamical friction. This study proposes an analytical model to predict the dynamical response of hosts as reflected in their density distribution and finds not only traditional wakes but also mirror images of over- and underdensities centered on the host. Our controlled N-body simulations with high resolutions verify the predictions of the analytical model. We apply our analytical model to the expected dynamical response of nearby interacting galaxy pairs, the Milky Way - Large Magellanic Cloud system and the M31 - M33 system.