Weighted density fields as improved probes of modified gravity models
  When it comes to searches for extensions to general relativity, large efforts
are being dedicated to accurate predictions for the power spectrum of density
perturbations. While this observable is known to be sensitive to the
gravitational theory, its efficiency as a diagnostic for gravity is
significantly reduced when Solar System constraints are strictly adhered to. We
show that this problem can be overcome by studying weigthed density fields. We
propose a transformation of the density field for which the impact of modified
gravity on the power spectrum can be increased by more than a factor of three.
The signal is not only amplified, but the modified gravity features are shifted
to larger scales which are less affected by baryonic physics. Furthermore, the
overall signal-to-noise increases, which in principle makes identifying
signatures of modified gravity with future galaxy surveys more feasible. While
our analysis is focused on modified gravity, the technique can be applied to
other problems in cosmology, such as the detection of neutrinos, the effects of
baryons or baryon acoustic oscillations.
