Degeneracy between primordial non-Gaussianity and interaction in the
  dark sector
  If dark energy and dark matter interact via exchange of energy and momentum,
then this may affect the galaxy power spectrum on large scales. When this
happens, it may be degenerate with the signal from primordial non-Gaussianity
via scale-dependent bias. We consider a class of interacting dark energy models
and show that the matter overdensity is scale-dependent on large scales. We
estimate the effective non-Gaussianity arising from the large-scale effects of
interaction in the dark sector. The signal of dark sector interaction can be
disentangled from a primordial non-Gaussian signal by measuring the power at
two redshifts.
