Temperature Structure and Mass-Temperature Scatter in Galaxy Clusters

Precision cosmology studies based on wide-field surveys of galaxy clusters benefit from constraints on intrinsic scatter in mass-observable relationships. In principle, two-parameter models combining direct measurements of galaxy-cluster structural variation with mass proxies such as X-ray luminosity and temperature can be used to constrain scatter in the relationship between the mass proxy and the cluster's halo mass and to measure the redshift evolution of that scatter. One candidate for quantifying cluster substructure is the intracluster medium temperature inhomogeneity inferred from X-ray spectral properties, an example of which is T HBR, the ratio of hardband to broadband spectral-fit temperatures. In this paper we test the effectiveness of T HBR as an indicator of scatter in the mass-temperature relation using 118 galaxy clusters simulated with radiative cooling and feedback. We find that, while T HBR is correlated with clusters' departures δln TX from the mean M-T X relation, the effect is modest.