Model Selection with Baryonic Acoustic Oscillations in the Lyman-alpha Forest

TL;DR

This study uses recent Lyman-alpha BAO measurements at high redshift to compare cosmological models, finding strong evidence against Milne and Einstein-de Sitter universes and supporting the R_h=ct model.

Contribution

It provides a direct model comparison based solely on Lyman-alpha BAO data, highlighting the consistency of R_h=ct with observations and challenging the standard LCDM model.

Findings

Milne and Einstein-de Sitter models are ruled out by data.

Lyman-alpha BAO measurements favor the R_h=ct universe.

Standard LCDM model is disfavored based on these measurements.

Abstract

The recent release of the final, complete survey of Lyman-alpha baryonic acoustic oscillation measurements provides the most significant and accurate data base for studying cosmic geometry at an effective redshift z_eff=2.334, which is inaccessible to other sources. In this Letter, we use these data to select among four distinct cosmologies: Planck LCDM, the R_h=ct universe, the Milne universe and Einstein-de Sitter. Given the breadth and depth of the Lyman-alpha study, this BAO measurement alone provides a strong model comparison, complementary to previous studies that combined Lyman-$\alpha$ data with measurements at lower redshifts. Though both approaches are useful, the latter tends to dilute the disparity between model predictions and the observations. We therefore examine how the models compare to each other strictly based on the BAO scale measured in the Lyman-alpha forest and background quasars. We find that Milne and Einstein-de Sitter are strongly ruled out by these data. There is also strong evidence disfavoring the standard model. The Lyman-alpha measurements are completely consistent with the cosmic geometry predicted by R_h=ct. As such, evidence continues to grow that the zero active mass condition from general relativity ought to be an essential ingredient in LCDM.