Geometry and growth contributions to cosmic shear observables
  We explore the sensitivity of weak lensing observables to the expansion
history of the universe and to the growth of cosmic structures, as well as the
relative contribution of both effects to constraining cosmological parameters.
We utilize ray-tracing dark-matter-only N-body simulations and validate our
technique by comparing our results for the convergence power spectrum with
analytic results from past studies. We then extend our analysis to non-Gaussian
observables which cannot be easily treated analytically. We study the
convergence (equilateral) bispectrum and two topological observables, lensing
peaks and Minkowski functionals, focusing on their sensitivity to the matter
density $\Omega_m$ and the dark energy equation of state $w$. We find that a
cancelation between the geometry and growth effects is a common feature for all
observables, and exists at the map level. It weakens the overall sensitivity by
up to a factor of 3 and 1.5 for $w$ and $\Omega_m$, respectively, with the
bispectrum worst affected. However, combining geometry and growth information
alleviates the degeneracy between $\Omega_m$ and $w$ from either effect alone.
As a result, the magnitude of marginalized errors remain similar to those
obtained from growth-only effects, but with the correlation between the two
parameters switching sign. These results shed light on the origin of
cosmology-sensitivity of non-Gaussian statistics, and should be useful in
optimizing combinations of observables.
