Physics of galactic colliders: high speed satellites in LCDM vs MONDian
  cosmology
  The statistics of high speed satellite galaxies, as reported in the recent
literature, can be a powerful diagnosis of the depth of the potential well of
the host halo, and hence discriminate between competing gravitational theories.
Naively one expects that high speed satellites are more common in Modified
Newtonian Dynamics (MOND) than in cold dark matter (CDM) since an isolated
MONDian system has an infinite potential well, while CDM halos have finite
potential wells. In this \textit{Letter} we report on an initial test of this
hypothesis in the context of the first generation of cosmological simulations
utilising a rigorous MONDian Poisson solver. We find that such high speed
encounters are approximately a factor of four more common in MOND than in the
concordance $\Lambda$CDM model of cosmic structure formation.
