Interpreting measurements of the anisotropic galaxy power spectrum

TL;DR

This paper develops a self-consistent framework to model wide-angle effects in the anisotropic galaxy power spectrum estimators, successfully detecting odd multipoles in BOSS DR12 data and improving cosmological measurements.

Contribution

It introduces a new framework that extends window function modeling to include wide-angle effects, enabling accurate analysis of anisotropic galaxy power spectra.

Findings

Successfully modeled wide-angle effects in BOSS DR12

Detected odd power spectrum multipoles with high significance

Highlights importance for cosmological measurements

Abstract

The most commonly used estimators of the anisotropic galaxy power spectrum employ Fast Fourier transforms, and rely on a specific choice of the line-of-sight that breaks the symmetry between the galaxy pair. This leads to wide-angle effects, including the presence of odd power spectrum multipoles like the dipole ($\ell = 1$) and octopole ($\ell = 3$). In Fourier-space these wide-angle effects also couple to the survey window function. We present a self-consistent framework extending the commonly used window function treatment to include the wide-angle effects. We show that our framework can successfully model the wide-angle effects in the BOSS DR12 dataset. We present estimators for the odd power spectrum multipoles and, detect these multipoles in BOSS DR12 with high significance. Understanding the impact of the wide-angle effects on the power spectrum multipoles is essential for many cosmological observables like primordial non-Gaussianity and the detection of General Relativistic effects and represents a potential systematic for measurements of Baryon Acoustic Oscillations and redshift-space distortions.