Re-capturing cosmic information
  Gravitational lensing of distant galaxies can be exploited to infer the
convergence field as a function of angular position on the sky. The statistics
of this field, much like that of the cosmic microwave background (CMB), can be
studied to extract information about fundamental parameters in cosmology, most
notably the dark energy in the Universe. Unlike the CMB, the distribution of
matter in the Universe which determines the convergence field is highly
non-Gaussian, reflecting the nonlinear processes which accompanied structure
formation. Much of the cosmic information contained in the initial field is
therefore unavailable to the standard power spectrum measurements. Here we
propose a method for re-capturing cosmic information by using the power
spectrum of a simple function of the observed (nonlinear) convergence field. We
adapt the approach of Neyrinck et al. (2009) to lensing by using a modified
logarithmic transform of the convergence field. The Fourier transform of the
log-transformed field has modes that are nearly uncorrelated, which allows for
additional cosmological information to be extracted from small-scale modes.
