On the Universality of the Bound-Zone Peculiar Velocity Profile
  A numerical evidence for the universality of the bound-zone peculiar velocity
profile in a LambdaCDM universe is presented. Analyzing the dark matter halo
catalogs from the Millennium-II simulation, we determine the average peculiar
velocity profiles of the objects located in the bound zones around massive
group-size halos at various redshifts and compare them to an analytic formula
characterized by two parameters, the amplitude and slope of the profile. The
best-fit values of the two parameters are found to be robust against the
changes of the mass scales and the key cosmological parameters. It is also
found that the amplitude and slope parameters of the bound-zone peculiar
velocity profile are constant but only in the limited ranges of redshifts. In
the dark matter dominated epoch corresponding to z> 0.6 the two parameters have
constant values. In the transition period corresponding to 0.2=< z=< 0.6 when
the density of Lambda begins to exceed that of dark matter the two parameters
grow almost linearly with redshifts. At later epochs z<0.2 when the
Lambda-domination prevails the two parameters regain constancy settling upon
higher constant values. Noting that the length of the transition period depends
on the amount of Lambda and speculating that the linear evolution of the
profile with redshifts in the transition period is a unique feature of the
Lambda-dominated universe, we suggest that the redshift evolution of the
bound-zone peculiar velocity profile should be a powerful local discriminator
of dark energy candidates.
