Observational Tests of the Mass-Temperature Relation for Galaxy Clusters

Donald J. Horner; Richard F. Mushotzky; Caleb A. Scharf

doi:10.1086/307437

paper

Observational Tests of the Mass-Temperature Relation for Galaxy Clusters

arXiv:astro-ph/9902151 · doi:10.1086/307437

Abstract

We examine the relationship between the mass and x-ray gas temperature of galaxy clusters using data drawn from the literature. Simple theoretical arguments suggest that the mass of a cluster is related to the x-ray temperature as $M \propto T_{x}^{3/2}$ . Virial theorem mass estimates based on cluster galaxy velocity dispersions seem to be accurately described by this scaling with a normalization consistent with that predicted by the simulations of Evrard, Metzler, & Navarro (1996). X-ray mass estimates which employ spatially resolved temperature profiles also follow a $T_{x}^{3/2}$ scaling although with a normalization about 40% lower than that of the fit to the virial masses. However, the isothermal $β$ -model and x-ray surface brightness deprojection masses follow a steeper $\propto T_{x}^{1.8 - 2.0}$ scaling. The steepness of the isothermal estimates is due to their implicitly assumed dark matter density profile of $ρ (r) \propto r^{- 2}$ at large radii while observations and simulations suggest that clusters follow steeper profiles (e.g., $ρ (r) \propto r^{- 2.4}$ ).

25 pages, 10 figures, accepted by ApJ

Observational Tests of the Mass-Temperature Relation for Galaxy Clusters

Abstract

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