Dynamics of the Magellanic Clouds in a LCDM Universe

摘要: We examine Milky Way-Magellanic Cloud systems selected from the Millennium-II Simulation in order to place orbits of Magellanic Clouds a cosmological context. Our analysis shows that satellites massive enough be LMC analogs are typically accreted at late times. Moreover, those early times and survive present have orbital properties discrepant with observed for LMC. The high velocity LMC, coupled dearth unbound seen simulation, argues mass MW's halo is unlikely less than 2 x 10^12 Msun. This conclusion further supported by statistics halos hosting masses, velocities, separations comparable show that: (1) SMC-mass objects not particularly uncommon MW-mass halos; (2) apparently angular momentum cosmologically unusual; (3) it rare MW host LMC-SMC binary system z=0, but speed pairs possible. Based on these results, we conclude was within past four Gyr currently making its first pericentric passage about MW.