Effects on the local dark matter distribution due to the Large Magellanic Cloud

TL;DR

This study models the impact of the Large Magellanic Cloud on the local dark matter distribution in the Milky Way, revealing significant velocity boosts and directional differences that can aid dark matter detection.

Contribution

It introduces an evolved dynamic model of the MW-LMC system, showing how the LMC influences local dark matter velocities and directions, which was not captured by static models.

Findings

LMC boosts local dark matter particle velocities by nearly 50%.

LMC particles have a distinguishable directional signature from MW particles.

Reflex motion causes a velocity boost in MW dark matter particles.

Abstract

We study the local dark matter distribution in two models for the Milky Way (MW)-Large Magellanic Cloud (LMC) interaction. The effect of the LMC on the local dark matter distribution is dependent on the evolution of the MW-LMC system, such that a static model is insufficient to accurately model the dark matter velocity distribution in the solar neighbourhood. An evolved model boosts local LMC dark matter particle velocities by nearly 50%, to a median value of $\approx750$km/s. MW dark matter particles also experience a velocity boost, which we identify as being caused by reflex motion owing to the infall of the LMC. We study the implications of LMC particles in the solar neighbourhood for dark matter detection experiments. Specifically, the directionality of LMC particles is distinguishable from the MW particles, with a difference in the apparent origin centroid location between the MW and LMC particles of $26\pm6 ^\circ$. This unique identifier, along with their high velocities, can be utilised by directional detectors to search for dark matter particles originating in the LMC.