Halo Pairs in the Millennium Simulation: Love & Deception
  In this work I investigate the statistical properties of a huge catalog of closely interacting pairs of dark matter haloes, extracted from the Millennium Simulation database. Only haloes that reach a minimum mass greater than 8.6 \times 10^10 Msun/h (corresponding to 100 particles) are considered. Close pairs are selected if they come within a critical distance dcrit. I explore the effects of replacing dcrit = 1 Mpc/h with 200 kpc/h on the evolution of separations, lifetimes, total masses and mass ratios of these pairs. 
Jorge Moreno
astro-ph.CO