Effect of the Milky Way on Magellanic Cloud Structure

A combination of analytic models and n-body simulations implies that thestructural evolution of the Large Magellanic Cloud (LMC) is dominated by itsdynamical interaction with the Milky Way. Although expected at some level, thescope of the involvement has significant observational consequences. First, LMCdisk orbits are torqued out of the disk plane, thickening the disk andpopulating a spheroid. The torque results from direct forcing by the Milky Waytide and, indirectly, from the drag between the LMC disk and its halo resultingfrom the induced precession of the LMC disk. The latter is a newly reportedmechanism that can affect all satellite interations. However, the overalltorque can not isotropize the stellar orbits and their kinematics remainsdisk-like. Such a kinematic signature is observed for nearly all LMCpopulations. The extended disk distribution is predicted to increase themicrolensing toward the LMC. Second, the disk's binding energy slowly decreasesduring this process, puffing up and priming the outer regions for subsequenttidal stripping. Because the tidally stripped debris will be spatiallyextended, the distribution of stripped stars is much more extended than the HIMagellanic Stream. This is consistent with upper limits to stellar densities inthe gas stream and suggests a different strategy for detecting the strippedstars. And, finally, the mass loss over several LMC orbits is predicted byn-body simulation and the debris extends to tens of kiloparsecs from the tidalboundary. Although the overall space density of the stripped stars is low,possible existence of such intervening populations have been recently reportedand may be detectable using 2MASS.