The baryon acoustic oscillation peak: a flexible standard ruler

TL;DR

This paper demonstrates that the BAO peak, traditionally used as a fixed standard ruler in cosmology, is actually flexible due to inhomogeneous curvature evolution, aligning with predictions from general relativity.

Contribution

It challenges the assumption of comoving space rigidity in the standard cosmological model by showing the BAO peak is flexible, consistent with inhomogeneous curvature evolution.

Findings

BAO peak is detected to be flexible.

Supports inhomogeneous curvature evolution during structure formation.

Aligns with general relativity predictions.

Abstract

For about a decade, the baryon acoustic oscillation (BAO) peak at about 105 Mpc/h has provided a standard ruler test of the LCDM cosmological model, a member of the Friedmann--Lemaitre--Robertson--Walker (FLRW) family of cosmological models---according to which comoving space is rigid. However, general relativity does not require comoving space to be rigid. During the virialisation epoch, when the most massive structures form by gravitational collapse, it should be expected that comoving space evolves inhomogeneous curvature as structure grows. The BAO peak standard ruler should also follow this inhomogeneous evolution if the comoving rigidity assumption is false. This "standard" ruler has now been detected to be flexible, as expected under general relativity.