Scale-dependent bias and mode coupling in redshift-space clustering near the BAO scale

TL;DR

This paper develops a simple, physically motivated model to accurately describe redshift-space clustering near the BAO scale, incorporating scale-dependent bias and mode coupling effects crucial for upcoming galaxy surveys.

Contribution

It introduces a model including scale-dependent bias and mode coupling effects, improving upon previous models by accounting for physical effects relevant to observational data.

Findings

Model accurately describes multipoles of 2pcf at BAO scales

Scale-dependent bias significantly impacts survey modeling

Mode coupling effects are less critical but still relevant

Abstract

The baryon acoustic oscillation (BAO) feature in the 2-point clustering of biased tracers in redshift space can be described in a model-agnostic manner, relying only on the assumption that nonlinear growth approximately smears this feature with a Gaussian kernel sourced by gravitationally driven bulk flows as in the Zel'dovich approximation. An explicit model that demonstrated this in recent work did not account for two physical effects that are very likely observationally relevant in the context of ongoing surveys, namely, the scale-dependence of linear Lagrangian density and velocity bias and the effects of mode coupling. We rectify this shortcoming in this paper by showing that a simple model including these effects is able to accurately describe the multipoles of the 2pcf of realistic tracer samples at BAO scales. Our results indicate that the effects of scale-dependent bias will be important to model for surveys such as DESI, while those of mode coupling are relatively less significant. Our model for scale-dependent bias and mode coupling, which is motivated by model-agnostic arguments from peaks theory and the Zel'dovich approximation, lies in the class of `Laplace-Gauss' expansions, making it straightforward to incorporate these effects in the model-agnostic inference framework mentioned above.