Galacto-forensic of LMC's orbital history as a probe for the dark matter potential in the outskirt of the Galaxy

TL;DR

This study re-evaluates the orbital history of the Large Magellanic Cloud using updated Galactic potential models, suggesting multiple past perigalacticon passages and highlighting the potential to probe dark matter distribution in the Galaxy's outskirts.

Contribution

It demonstrates that the LMC's orbital history is sensitive to dark matter distribution and that refined models can reveal multiple past passages, challenging previous first-perigalacticon assumptions.

Findings

LMC may have had multiple perigalacticon passages.

Orbital history depends on dark matter distribution beyond current Galactic distance.

Accurate LMC motion measurements can inform dark matter models.

Abstract

The 3D observed velocities of the Large and Small Magellanic Clouds(LMC and SMC) provide an opportunity to probe the Galactic potential in the outskirt of the Galactic halo. Based on a canonical NFW model of the Galactic potential, Besla et al.(2007) reconstructed LMC and SMC's orbits and suggested that they are currently on their first perigalacticon passage about the Galaxy. Motivated by several recent revisions of the Sun's motion around the Galactic center, we re-examine the LMC's orbital history and show that it depends sensitively on the dark-matter's mass distribution beyond its present Galactic distance. We utilize results of numerical simulations to consider a range of possible structural and evolutionary models for the Galactic potentials. We find that within the theoretical and observational uncertainties, it is possible for the LMC to have had multiple perigalacticon passages on the Hubble time scale, especially if the Galactic circular velocity at the location of the Sun is greater than $\sim 228$km s$^{-1}$. Based on these models, a more accurate determination of the LMC's motion may be used to determine the dark matter distribution in the outskirt of the Galactic halo.