Disantangling the effects of Doppler velocity and primordial
  non-Gaussianity in galaxy power spectra
  We study the detectability of large-scale velocity effects on galaxy
clustering, by simulating galaxy surveys and combining the clustering of
different types of tracers of large-scale structure. We employ a set of
lognormal mocks that simulate a $20.000$ deg$^2$ near-complete survey up to
$z=0.8$, in which each galaxy mock traces the spatial distribution of dark
matter of that mock with a realistic bias prescription. We find that the ratios
of the monopoles of the power spectra of different types of tracers carry most
of the information that can be extracted from a multi-tracer analysis. In
particular, we show that with a multi-tracer technique it will be possible to
detect velocity effects with $\gtrsim 3 \sigma$. Finally, we investigate the
degeneracy of these effects with the (local) non-Gaussianity parameter $f_{\rm
NL}$, and how large-scale velocity contributions could be mistaken for the
signatures of primordial non-Gaussianity.
