Testing X-ray Measurements of Galaxy Cluster Gas Mass Fraction Using the Cosmic Distance-Duality Relation

TL;DR

This paper tests the consistency of galaxy cluster gas mass fraction measurements with the cosmic distance-duality relation using supernova data, revealing some datasets align with standard cosmology while others suggest alternative models.

Contribution

It introduces a new method to verify X-ray gas mass fraction data against the distance-duality relation without redshift parameterizations, enhancing cosmological model testing.

Findings

LaRoque et al.'s data aligns with standard cosmology within 1-sigma

Ettori et al.'s data shows significant deviation, favoring an $ ext{O}_ ext{L}=0$ cosmology

Method proves feasible with Allen et al.'s samples

Abstract

We propose a consistency test of some recent X-ray gas mass fraction ($f_{\rm{gas}}$) measurements in galaxy clusters, using the cosmic distance-duality relation, $\eta_{\rm{theory}}=\dl(1+z)^{-2}/\da$, with luminosity distance ($\dl$) data from the Union2 compilation of type Ia supernovae. We set $\eta_{\rm{theory}}\equiv1$, instead of assigning any redshift parameterizations to it, and constrain the cosmological information preferred by $f_{\rm{gas}}$ data along with supernova observations. We adopt a new binning method in the reduction of the Union2 data, in order to minimize the statistical errors. Four data sets of X-ray gas mass fraction, which are reported by Allen et al. (2 samples), LaRoque et al. and Ettori et al., are detailedly analyzed against two theoretical modelings of $f_{\rm{gas}}$. The results from the analysis of Allen et al.'s samples prove the feasibility of our method. It is found that the preferred cosmology by LaRoque et al.'s sample is consistent with its reference cosmology within 1-$\sigma$ confidence level. However, for Ettori et al.'s $f_{\rm{gas}}$ sample, the inconsistency can reach more than 3-$\sigma$ confidence level and this dataset shows special preference to an $\Ol=0$ cosmology.