Constraining Anisotropic Baryon Oscillations

TL;DR

This paper develops a method to separately measure the angular diameter distance and Hubble parameter from anisotropic baryon acoustic oscillations, improving constraints by analyzing both monopole and quadrupole spectra.

Contribution

It introduces a novel approach to break the degeneracy between d_A and H by utilizing the quadrupole power spectrum, extending previous monopole-focused analyses.

Findings

Quadrupole spectrum is sensitive to the d_A H warping mode.

Method verified on N-body simulations.

Fractional accuracy of ~3/√V% for d_A H measurement.

Abstract

We present an analysis of anisotropic baryon acoustic oscillations and elucidate how a mis-estimation of the cosmology, which leads to incorrect values of the angular diameter distance, d_A, and Hubble parameter, H, manifest themselves in changes to the monopole and quadrupole power spectrum of biased tracers of the density field. Previous work has focused on the monopole power spectrum, and shown that the isotropic "dilation" combination d_A^2/H is robustly constrained by an overall shift in the scale of the baryon feature. We extend this by demonstrating that the quadrupole power spectrum is sensitive to an anisotropic "warping" mode d_A H, allowing one to break the degeneracy between d_A and H. We describe a method for measuring this warping, explicitly marginalizing over the form of redshift space distortions. We verify this method on N-body simulations and estimate that d_A H can be measured with a fractional accuracy of ~ 3/sqrt(V) % where the survey volume is estimated in (Gpc/h)^3.