Optimal Redshift Weighting For Redshift Space Distortions

TL;DR

This paper introduces an efficient, optimized weighting method for analyzing redshift space distortions in galaxy surveys, enabling precise measurement of cosmological evolution without redshift binning.

Contribution

It develops a new set of galaxy-weights optimized for measuring redshift-dependent cosmological parameters, improving analysis efficiency and robustness.

Findings

Weights effectively measure deviations from ΛCDM

Method reduces systematic errors in RSD analysis

Robust against variations in galaxy bias

Abstract

The low statistical errors on cosmological parameters promised by future galaxy surveys will only be realised with the development of new, fast, analysis methods that reduce potential systematic problems to low levels. We present an efficient method for measuring the evolution of the growth of structure using Redshift Space Distortions (RSD), that removes the need to make measurements in redshift shells. We provide sets of galaxy-weights that cover a wide range in redshift, but are optimised to provide differential information about cosmological evolution. These are derived to optimally measure the coefficients of a parameterisation of the redshift-dependent matter density, which provides a framework to measure deviations from the concordance $\Lambda$CDM cosmology, allowing for deviations in both geometric and/or growth. We test the robustness of the weights by comparing with alternative schemes and investigate the impact of galaxy bias. We extend the results to measure the combined anisotropic Baryon Acoustic Oscillation (BAO) and RSD signals.