Scale-dependent Galaxy Bias

TL;DR

This paper introduces a simple deterministic model showing how galaxy formation feedback can cause scale-dependent galaxy bias, affecting large-scale structure observations and mimicking stochastic effects.

Contribution

The paper presents a new heuristic, deterministic model explaining scale-dependent galaxy bias due to feedback effects in galaxy formation.

Findings

Bias features can mimic baryonic wiggles in power spectra.

Deterministic processes can produce apparent stochasticity in galaxy distribution.

Large-scale bias modulation arises naturally from galaxy formation feedback.

Abstract

We present a simple heuristic model to demonstrate how feedback related to the galaxy formation process can result in a scale-dependent bias of mass versus light, even on very large scales. The model invokes the idea that galaxies form initially in locations determined by the local density field, but the subsequent formation of galaxies is also influenced by the presence of nearby galaxies that have already formed. The form of bias that results possesses some features that are usually described in terms of stochastic effects, but our model is entirely deterministic once the density field is specified. Features in the large-scale galaxy power spectrum (such as wiggles that might in an extreme case mimic the effect of baryons on the primordial transfer function) could, at least in principle, arise from spatial modulations of the galaxy formation process that arise naturally in our model. We also show how this fully deterministic model gives rise to apparently stochasticity in the galaxy distribution.