A low-redshift galaxy cluster X-ray Temperature Function incorporating Suzaku data

TL;DR

This study presents Suzaku X-ray observations of 14 low-redshift galaxy clusters, combining them with existing data to analyze the local cluster temperature function and its implications for cosmology.

Contribution

First Suzaku-based temperature measurements for these clusters, expanding the low-redshift cluster sample and refining the local temperature function.

Findings

Suzaku temperatures agree with other missions.

Slightly lower space densities at T<5 keV.

Possible deficit of clusters with 4.5-5.5 keV temperatures.

Abstract

We present the first results of a survey of 14 low redshift galaxy clusters using Suzaku. Although luminous (L_x> 1\times 10^{43} erg s^{-1} (0.1-2.4 keV)), these clusters have no prior pointed X-ray data. Together with 47 other systems they form a flux limited sample (f_x >1.0 \times 10^{-11} erg s^{-1}cm^{-2} (0.1-2.4 keV)) with z<0.1 in the northern celestial hemisphere. Using this total sample we evaluate the local $L-T$ relationship and the local cluster temperature function. Suzaku temperature measurements appear to be in accord with those of other missions. General agreement is found with other published estimates of the low redshift cluster temperature function, however the sample used here exhibits slightly lower space densities at gas temperatures below 4-5 keV. We find a corresponding deficit in the number of clusters with temperatures between approximately 4.5 and 5.5 keV. Although at low significance, a similar feature exists in previous low redshift cluster datasets. We suggest that low-redshift cluster samples, while crucial for calibrating precision cosmology measurements, must be used with caution due to their limited size and susceptibility to the effects of cosmic variance.