X-ray galaxy clusters abundance and mass temperature scaling

TL;DR

This study uses X-ray galaxy cluster temperature data combined with CMB observations to simultaneously constrain cosmological parameters and the mass-temperature relation, finding a self-consistent model with improved calibration.

Contribution

It introduces a method to jointly estimate cosmological parameters and the mass-temperature relation using local X-ray cluster data and MCMC techniques.

Findings

The temperature function is well reproduced with a free calibration parameter.

The cosmological parameters remain consistent with previous Planck results.

The mass-temperature relation calibration suggests masses are 75% larger than previous X-ray estimates.

Abstract

The abundance of clusters of galaxies is known to be a potential source of cosmological constraints through their mass function. In the present work, we examine the information that can be obtained from the temperature distribution function of X-ray clusters. For this purpose, the mass-temperature ($M$-$T$) relation and its statistical properties are critical ingredients. Using a combination of cosmic microwave background (CMB) data from Planck and our estimations of X-ray cluster abundances, we use Markov chain Monte Carlo (MCMC) techniques to estimate the $\Lambda$CDM cosmological parameters and the mass to X-ray temperature scaling relation simultaneously. We determine the integrated X-ray temperature function of local clusters using flux-limited surveys. A local comprehensive sample was build from the BAX X-ray cluster database, allowing us to estimate the local temperature distribution function above $\sim$1 keV. We model the expected temperature function from the mass function and the $M$-$T$ scaling relation. We then estimate the cosmological parameters and the parameters of the $M$-$T$ relation (calibration and slope) simultaneously. The measured temperature function of local clusters in the range $\sim\!\!1$-$10$ keV is well reproduced once the calibration of the $M$-$T$ relation is treated as a free parameter, and therefore is self-consistent with respect to the $\Lambda$CDM cosmology. The best-fit values of the standard cosmological parameters as well as their uncertainties are unchanged by the addition of clusters data. The calibration of the mass temperature relation, as well as its slope, are determined with $\sim10\%$ statistical uncertainties. This calibration leads to masses that are $\sim\!\!75\%$ larger than X-ray masses used in Planck.