Cosmic Shear as a Probe of Galaxy Formation Physics
  We evaluate the potential for current and future cosmic shear measurements
from large galaxy surveys to constrain the impact of baryonic physics on the
matter power spectrum. We do so using a model-independent parameterization that
describes deviations of the matter power spectrum from the dark-matter-only
case as a set of principal components that are localized in wavenumber and
redshift. We perform forecasts for a variety of current and future datasets,
and find that at least ~90% of the constraining power of these datasets is
contained in no more than nine principal components. The constraining power of
different surveys can be quantified using a figure of merit defined relative to
currently available surveys. With this metric, we find that the final Dark
Energy Survey dataset (DES Y5) and the Hyper Suprime Cam Survey will be roughly
an order of magnitude more powerful than existing data in constraining baryonic
effects. Upcoming Stage IV surveys (LSST, Euclid, and WFIRST) will improve upon
this by a further factor of a few. We show that this conclusion is robust to
marginalization over several key systematics. The ultimate power of cosmic
shear to constrain galaxy formation is dependent on understanding systematics
in the shear measurements at small (sub-arcminute) scales. If these systematics
can be sufficiently controlled, cosmic shear measurements from DES Y5 and other
future surveys have the potential to provide a very clean probe of galaxy
formation and to strongly constrain a wide range of predictions from modern
hydrodynamical simulations.
