Constraining H0 from Lyman-alpha Forest and Baryon Acoustic Oscillations

TL;DR

This paper introduces a new method to estimate the Hubble constant using Lyman-alpha forest data, which, when combined with BAO analysis, can potentially provide an independent and competitive measurement of H0.

Contribution

It proposes a semi-analytical model for the Lyman-alpha forest to constrain H0 and Omega_m, and demonstrates how combining with BAO data can break parameter degeneracies.

Findings

Constraints on H0: 0.58 to 0.91

Constraints on Omega_m: 0.215 to 0.245

Method shows potential with larger samples and better IGM knowledge

Abstract

A new method is proposed to measure the Hubble constant H0 through the mean transmitted flux observed from high redshift quasars. A semi-analytical model for the cosmological-independent volume density distribution function is adopted which allows one to obtain constraints over the cosmological parameters once a moderate knowlegde of the InterGalactic Medium (IGM) parameters is assumed. By assuming a flat LCDM cosmology, we show that such method alone cannot provide good constraints on the pair of free parameters (h, Omega_m). However, it is possible possible to break the degeneracy on the mass density parameter by applying a joint analysis involving the baryon acoustic oscillations (BAOs). Our analysis based on two different samples of Lyman-alpha forest restricts the parameters on the intervals 0.58 < h < 0.91 and 0.215 < Omega_m < 0.245 (1 sigma). Although the constraints are weaker comparatively to other estimates, we point out that with a bigger sample and a better knowledge of the IGM this method may present competitive results to measure the Hubble constant independently of the cosmic distance ladder.