Cosmological direct detection of dark energy: non-linear structure
  formation signatures of dark energy scattering with visible matter
  We consider the recently proposed possibility that dark energy (DE) and
baryons may scatter through a pure momentum exchange process, leaving the
background evolution unaffected. Earlier work has shown that, even for
barn-scale cross-sections, the imprints of this scattering process on linear
cosmological observables is too tiny to be observed. We therefore turn our
attention to non-linear scales, and for the first time investigate the
signatures of DE-baryon scattering on the non-linear formation of cosmic
structures, by running a suite of large N-body simulations. The observables we
extract include the non-linear matter power spectrum, halo mass function, and
density and baryon fraction profiles of halos. We find that in the non-linear
regime the signatures of DE-baryon scattering are significantly larger than
their linear counterparts, due to the important role of angular momentum in
collapsing structures, and potentially observable. The most promising
observables in this sense are the baryon density and baryon fraction profiles
of halos, which can potentially be constrained by a combination of kinetic
Sunyaev-Zeldovich (SZ), thermal SZ, and weak lensing measurements. Overall, our
results indicate that future prospects for cosmological and astrophysical
direct detection of non-gravitational signatures of dark energy are extremely
bright.
