The quasi-linear nearby Universe
  The local Universe provides a unique opportunity for testing cosmology and
theories of structure formation. To facilitate this opportunity we present a
new method for the reconstruction of the quasi-linear matter density and
velocity fields from galaxy peculiar velocities and apply it to the
Cosmicflows-2 data. The method consists of constructing an ensemble of
cosmological simulations, constrained by the standard cosmological model and
the observational data. The quasi-linear density field is the geometric mean
and variance of the fully non-linear density fields of the simulations. The
main nearby clusters (Virgo, Centaurus, Coma), superclusters (Shapley,
Perseus-Pisces) and voids (Dipole Repeller) are robustly reconstructed.
Galaxies are born biased with respect to the underlying dark matter
distribution. Using our quasi-linear framework we demonstrate that the
luminosity-weighted density field derived from the 2M++ redshift compilations
is non-linearly biased with respect to the matter density field. The bias
diminishes in the linear regime.
