Disentangling non-Gaussianity, bias, and general relativistic effects in the galaxy distribution

Abstract

Local non-Gaussianity, parametrized by ${f}_{\mathrm{NL}}$, introduces a scale-dependent bias that is strongest at large scales, precisely where general relativistic (GR) effects also become significant. With future data, it should be possible to constrain ${f}_{\mathrm{NL}}=\mathcal{O}(1)$ with high redshift surveys. GR corrections to the power spectrum and ambiguities in the gauge used to define bias introduce effects similar to ${f}_{\mathrm{NL}}=\mathcal{O}(1)$, so it is essential to disentangle these effects. For the first time in studies of primordial non-Gaussianity, we include the consistent GR calculation of galaxy power spectra, highlighting the importance of a proper definition of bias. We present observable power spectra with and without GR corrections, showing that an incorrect definition of bias can mimic non-Gaussianity. However, these effects can be distinguished by their different redshift and scale dependence, so as to extract the true primordial non-Gaussianity.