Dynamics of the Magellanic Clouds in a LCDM Universe

Understand

We examine Milky Way-Magellanic Cloud systems selected from the Millennium-II Simulation in order to place the orbits of the Magellanic Clouds in a cosmological context.

• Our analysis shows that satellites massive enough to be LMC analogs are typically accreted at late times.
• Moreover, those that are accreted at early times and survive to the present have orbital properties that are discrepant with those observed for the LMC.
• The high velocity of the LMC, coupled with the dearth of unbound orbits seen in the simulation, argues that the mass of the MW's halo is unlikely to be less than 2 x 10^12 Msun.