A possible explanation of vanishing halo velocity bias
  Recently Chen et al. (2018, ApJ, 861, 58) accurately determined the volume
weighted halo velocity bias in simulations, and found that the deviation of
velocity bias from unity is much weaker than the peak model prediction. Here we
present a possible explanation of this vanishing velocity bias. The starting
point is that, halos are peaks in the low redshift {\it non-Gaussian} density
field with smoothing scale $R_{\Delta}$ (virial radius), instead of peaks in
the high redshift initial {\it Gaussian} density field with a factor of
$\mathcal{O}(\Delta^{1/3})$ larger smoothing scale. Based on the approximation
that the density field can be Gaussianized by a local and monotonic
transformation, we extend the peak model to the non-Gaussian density field and
derive the analytical expression of velocity dispersion and velocity power
spectrum of these halos. The predicted deviation of velocity bias from unity is
indeed much weaker than the previous prediction, and the agreement with the
simulation results is significantly improved.
