A new consistency test for $\Lambda$CDM cosmology using galaxy surveys

TL;DR

This paper introduces a novel consistency test for the $ ext{Lambda}$CDM model utilizing galaxy survey data, specifically comparing RSD and BAO measurements to identify potential deviations.

Contribution

The paper presents a new method to test $ ext{Lambda}$CDM by comparing RSD peak positions with BAO predictions, reducing systematics compared to traditional approaches.

Findings

Test demonstrated with DESI simulated data

Complementary to background observable tests

Less affected by RSD analysis systematics

Abstract

We propose a new consistency test for the $\Lambda$CDM cosmology using baryonic acoustic oscillations (BAO) and redshift space distortion (RSD) measurements from galaxy redshift surveys. Specifically, we determine the peak position of $f\sigma_8(z)$ in redshift $z$ offered by a RSD measurement, and compare it to the one predicted by the BAO observables assuming a flat $\Lambda$CDM cosmology. We demonstrate this new test using the simulated data for the DESI galaxy survey, and argue that this test complements those using the background observables alone, and is less subject to systematics in the RSD analysis, compared to traditional methods using values of $f\sigma_8(z)$ directly.