Unveiling the Hubble Constant through Galaxy Cluster Gas Mass Fractions

TL;DR

This paper estimates the Hubble constant using galaxy cluster gas mass fractions, supernovae data, and cosmic distance relations, providing a cosmology-independent measurement with potential for improved future precision.

Contribution

It introduces a method combining gas mass fractions and galaxy clustering to estimate Hubble's constant independently of specific cosmological models.

Findings

Estimated H_0 = 72.7^{+6.3}_{-5.6} km/s/Mpc at 68% CL

Future measurements could reach 5% precision on H_0

Analysis shows the impact of data quantity and quality on H_0 accuracy

Abstract

In this work, we obtain Hubble constant ($H_0$) estimates by using two galaxy cluster gas mass fraction measurement samples, Type Ia supernovae luminosity distances, and the validity of the cosmic distance duality relation. Notably, the angular diameter distance (ADD) to each galaxy cluster in the samples is determined by combining its gas mass fraction measurement with galaxy clustering observations, more precisely, the $\Omega_b/\Omega_m$ ratio. Such a combination results in a $H_0$ estimate that is independent of a specific cosmological framework. In one of the samples, the gas fraction measurements were calculated in spherical shells at radii near $r_{\rm 2500}$ (44 data points), while in the other (103 data points) the measurements were calculated within $ r_{\rm 500}$. We find $H_0=72.7^{+6.3}_{-5.6}$ km/s/Mpc at 68\% CL for the joint analysis of these data sets. We also investigate the impact on the $H_0$ determination by exploring the precision and number of gas mass fraction data by performing a data Monte Carlo simulation. Our simulations show that future measurements could achieve a precision of up to 5\% for $H_0$.