The Clustering of Orbital Poles Induced by the LMC: Hints for the Origin
  of Planes of Satellites
  A significant fraction of Milky Way (MW) satellites exhibit phase-space
properties consistent with a coherent orbital plane. Using tailored N--body
simulations of a spherical MW halo that recently captured a massive (1.8$\times
10^{11}$M$\odot$) LMC-like satellite, we identify the physical mechanisms that
may enhance the clustering of orbital poles of objects orbiting the MW. The LMC
deviates the orbital poles of MW dark matter (DM) particles from the
present-day random distribution. Instead, the orbital poles of particles beyond
$R\approx 50$kpc cluster near the present-day orbital pole of the LMC along a
sinusoidal pattern across the sky. The density of orbital poles is enhanced
near the LMC by a factor $\delta \rho_{max}$=30\%(50\%) with respect to
underdense regions, and $\delta \rho_{iso}$=15\%(30\%) relative to the isolated
MW simulation (no LMC) between 50-150 kpc (150-300 kpc). The clustering appears
after the LMC's pericenter ($\approx$ 50 Myr ago, 49 kpc) and lasts for at
least 1 Gyr. Clustering occurs because of three effects: 1) the LMC shifts the
velocity and position of the central density of the MW's halo and disk; 2) the
DM dynamical friction wake and collective response induced by the LMC changes
the kinematics of particles; 3) observations of particles selected within
spatial planes suffer from a bias, such that measuring orbital poles in a great
circle in the sky enhances the probability of their orbital poles being
clustered. This scenario should be ubiquitous in hosts that recently captured a
massive satellite (at least $\approx$ 1:10 mass ratio), causing the clustering
of orbital poles of halo tracers.
