  Primordial non-Gaussianity generated by additional fields present during
inflation offers a compelling observational target for galaxy surveys. These
fields are of significant theoretical interest since they offer a window into
particle physics in the inflaton sector. They also violate the single-field
consistency conditions and induce a scale-dependent bias in the galaxy power
spectrum. In this paper, we explore this particular signal for light scalar
fields and study the prospects for measuring it with galaxy surveys. We find
that the sensitivities of current and future surveys are remarkably stable for
different configurations, including between spectroscopic and photometric
redshift measurements. This is even the case at non-zero masses where the
signal is not obviously localized on large scales. For realistic galaxy number
densities, we demonstrate that the redshift range and galaxy bias of the sample
have the largest impact on the sensitivity in the power spectrum. These results
additionally motivated us to explore the potentially enhanced sensitivity of
Vera Rubin Observatory's LSST through multi-tracer analyses. Finally, we apply
this understanding to current data from the last data release of the Baryon
Oscillation Spectroscopic Survey (BOSS DR12) and place new constraints on light
fields coupled to the inflaton.
