Constraining modified growth patterns with tomographic surveys
  Viable models of modified gravity designed to produce cosmic acceleration at
the current epoch, closely mimic the $\Lambda$CDM model at the level of
background cosmology. However, this degeneracy is generically broken at the
level of linear perturbations, where the modifications induce a peculiar
scale-dependent pattern. A similar pattern is expected in models of coupled
dark energy. I present the main results published in Pogosian and Silvestri
[1], on the growth of structure in f(R) theories of gravity, and in Zhao et al.
[2], on the potential of upcoming and future tomographic surveys to detect
departures from the growth of cosmic structure expected within General
Relativity with a cosmological constant.
