Goodness-of-fit analysis of the Cosmicflows-2 database of velocities
  The goodness-of-fit (GoF) of the Cosmicflows-2 (CF2) database of peculiar
velocities with the LCDM standard model of cosmology is presented. Standard
application of the Chi^2 statistics of the full database, of its 4,838 data
points, is hampered by the small scale nonlinear dynamics which is not
accounted for by the (linear regime) velocity power spectrum. The bulk velocity
constitutes a highly compressed representation of the data which filters out
the small scales non-linear modes. Hence the statistics of the bulk flow
provides an efficient tool for assessing the GoF of the data given a model. The
particular approach introduced here is to use the (spherical top-hat window)
bulk velocity extracted from the Wiener filter reconstruction of the 3D
velocity field as a linear low pass filtered highly compressed representation
of the CF2 data. An ensemble 2250 random linear realizations of the WMAP/LCDM
model has been used to calculate the bulk velocity auto-covariance matrix. We
find that the CF2 data is consistent with the WMAP/LCDM model to better than
the 2 sigma confidence limits. This provides a further validation that the CF2
database is consistent with the standard model of cosmology.
