# Disantangling the effects of Doppler velocity and primordial non-Gaussianity in galaxy power spectra

## TL;DR

This paper investigates how large-scale velocity effects influence galaxy clustering measurements, demonstrating that multi-tracer analysis can detect these effects and distinguishing them from primordial non-Gaussianity signatures.

## Contribution

It introduces a simulation-based approach to disentangle velocity effects from primordial non-Gaussianity in galaxy power spectra using multi-tracer techniques.

## Key findings

- Velocity effects detectable at >3 sigma with multi-tracer analysis.
- Ratios of monopoles of different tracers contain key information.
- Large-scale velocity effects can mimic primordial non-Gaussianity signals.

## Abstract

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.