Consistency of the nonflat $\Lambda$CDM model with the new result from BOSS

TL;DR

This study examines whether a non-flat DM model with positive curvature can resolve the tension between BOSS measurements of the universe's expansion rate at high redshift and the predictions of the flat DM model, using observational data.

Contribution

It demonstrates that a non-flat DM model with positive curvature can naturally alleviate the tension observed in BOSS data, and assesses its consistency with Planck, WP, and BAO observations.

Findings

Non-flat DM model fits BOSS high-redshift data better.

Planck+WP data constrain the non-flat DM model effectively.

Poor fit to BAO transverse measurements persists.

Abstract

Using 137,562 quasars in the redshift range $2.1\leq z\leq3.5$ from the Data Release 11 (DR11) of the Baryon Oscillation Spectroscopic Survey (BOSS) of Sloan Digital Sky Survey (SDSS)-III, the BOSS-SDSS collaboration estimated the expansion rate $H(z=2.34)=222\pm7$ km/s/Mpc of Universe, and reported that this value is in tension with the predictions of flat $\Lambda$CDM model at around 2.5$\sigma$ level. In this paper, we briefly describe some attempts made in the literature to relieve the tension, and show that the tension can naturally be alleviated in non-flat $\Lambda$CDM model with positive curvature. We also perform the observational consistency check by considering the constraints on the non-flat $\Lambda$CDM model from Planck,WP and BAO data. We find that the non-flat $\Lambda$CDM model constrained with Planck+WP data fits better to the line of sight measurement $H(z=2.34)=222\pm7$ km/s/Mpc, but only at the expense of still having a poor fit to the BAO transverse measurements.