The Milky Way's rowdy neighbours: The effects of the Large Magellanic Cloud and Sagittarius Dwarf on the Milky Way Disc

TL;DR

This study uses high-resolution N-body simulations to analyze how the Large Magellanic Cloud and Sagittarius Dwarf galaxy influence the Milky Way's stellar disc, revealing their distinct and additive effects on galactic structure and kinematics.

Contribution

It provides a comprehensive simulation suite to independently and jointly study satellite interactions with the Milky Way, highlighting the importance of including both satellites in models.

Findings

LMC and Sgr effects are distinct and additive.

Sgr reproduces observed radial velocity waves.

Both satellites significantly influence MW disc structure.

Abstract

The Milky Way (MW) is a barred spiral galaxy shaped by tidal interactions with its satellites. The Large Magellanic Cloud (LMC) and the Sagittarius Dwarf galaxy (Sgr) are the dominant influences at the present day. This paper presents a suite of four 10^9 particle N-body simulations, illustrating the response of the stellar disc of the MW to the close approach of the LMC and the merger of Sgr into the MW. The suite is intended to provide a resource for others to study the complex interactions between the MW and its satellites independently and together, in comparison to an isolated disc control simulation. The high temporal and mass resolution allows for a quantitative Fourier decomposition of the stellar kinematics, disentangling the individual influence of each satellite on the MW. In our preliminary analysis, we find that the influences from the LMC and Sgr on the disc of the MW appear distinct, additive, and separable within our tailored simulations. Notably, the corrugations induced by Sgr reproduce the large radial velocity wave seen in the data (Eilers et al. 2020). Overall, our findings emphasise the need to include both satellites when modelling the present-day state of the MW structure and kinematics