The Misalignments between Matter and Galaxy Distributions in Triaxial
  Clusters: A Signature of a Possible Fifth Force?
  The standard structure formation model based on a LCDM cosmology predicts
that the galaxy clusters have triaxial shapes and that the cluster galaxies
have a strong tendency to be located preferentially along the major axes of
host cluster's dark matter distributions due to the gravitational tidal effect.
The predicted correlations between dark matter and galaxy distributions in
triaxial clusters are insensitive to the initial cosmological parameters and to
the galaxy bias, and thus can provide a unique test-bed for the nonlinear
structure formation of the LCDM cosmology. Recently, Oguri et al. determined
robustly the dark matter distributions in the galaxy clusters using the two
dimensional weak lensing shear fitting and showed that the orientations of the
cluster galaxy distributions are only very weakly correlated with those of the
underlying dark matter distributions determined robustly, which is in contrast
to with the LCDM-based prediction. We reanalyze and compare quantitatively the
observational result with the LCDM-based prediction from the Millennium Run
simulation with the help of the bootstrap resampling and generalized
chi^{2}-statistics. The hypothesis that the observational result is consistent
with the LCDM-based prediction is ruled out at the 99% confidence level. A
local fifth force induced by a non-minimal coupling between dark energy and
dark matter might be responsible for the observed misalignments between dark
matter and galaxy distributions in triaxial clusters.
