New constraints on H_0 and Omega_M from SZE/X-RAY data and Baryon Acoustic Oscillations

TL;DR

This study combines Sunyaev-Zel'dovich effect, X-ray data, and baryon acoustic oscillations to refine measurements of the Hubble constant and matter density in a flat universe, addressing degeneracies and geometric assumptions.

Contribution

It provides a new joint analysis method to constrain H_0 and Omega_m using SZE/X-ray data and BAO, improving parameter estimates in cosmology.

Findings

H_0 = 0.765^{+0.035}_{-0.033} km/s/Mpc

Omega_m = 0.27^{+0.03}_{-0.02}

Joint analysis reduces degeneracies in cosmological parameters

Abstract

The Hubble constant, $H_0$, sets the scale of the size and age of the Universe and its determination from independent methods is still worthwhile to be investigated. In this article, by using the Sunyaev-Zel`dovich effect and X-ray surface brightness data from 38 galaxy clusters observed by Bonamente {\it{et al.}} (2006), we obtain a new estimate of $H_0$ in the context of a flat $\Lambda$CDM model. There is a degeneracy on the mass density parameter ($\Omega_{m}$) which is broken by applying a joint analysis involving the baryon acoustic oscillations (BAO) as given by Sloan Digital Sky Survey (SDSS). This happens because the BAO signature does not depend on $H_0$. Our basic finding is that a joint analysis involving these tests yield $H_0= 0.765^{+0.035}_{-0.033}$ km s$^{-1}$ Mpc$^{-1}$ and $\Omega_{m}=0.27^{+0.03}_{-0.02}$. Since the hypothesis of spherical geometry assumed by Bonamente {\it {et al.}} is questionable, we have also compared the above results to a recent work where a sample of triaxial galaxy clusters has been considered.