Galaxy Bias and Primordial Non-Gaussianity

TL;DR

This paper systematically analyzes how primordial non-Gaussianity influences galaxy bias, establishing a complete bias expansion, and explores observational signatures like scale-dependent bias and anisotropic effects.

Contribution

It introduces a comprehensive bias expansion framework for non-Gaussian initial conditions and links galaxy bias features to fundamental principles like the equivalence principle.

Findings

Bias expansion is closed under renormalization.

Relation between scale-dependent bias and bispectrum dipole is established.

Imprints of anisotropic non-Gaussianity are discussed.

Abstract

We present a systematic study of galaxy biasing in the presence of primordial non-Gaussianity. For a large class of non-Gaussian initial conditions, we define a general bias expansion and prove that it is closed under renormalization, thereby showing that the basis of operators in the expansion is complete. We then study the effects of primordial non-Gaussianity on the statistics of galaxies. We show that the equivalence principle enforces a relation between the scale-dependent bias in the galaxy power spectrum and that in the dipolar part of the bispectrum. This provides a powerful consistency check to confirm the primordial origin of any observed scale-dependent bias. Finally, we also discuss the imprints of anisotropic non-Gaussianity as motivated by recent studies of higher-spin fields during inflation.