| Galaxy cluster masses play an important role in addressing fundamental physical and cosmological problems. A vital tool for the measurement of cluster masses is the diffuse hot intergalactic medium which can be detected primarily through its bright X-ray emission. A variety of models are used to describe the distribution of the gas, from the simple isothermal beta model to more complex models that describe the X-ray properties.;I introduce a physically motivated model of the diffuse intergalactic medium in galaxy clusters based on an analytic distribution for the cluster mass density. This mass density is combined with a polytropic equation of state for the gas, to provide self-consistent density, temperature and pressure profiles for a plasma in hydrostatic equilibrium. In this work I derive analytic radial profiles for the physical quantities (temperature, density and pressure) relevant to X-ray and Sunyaev Zeldovich Effect (SZE) observations, and present an application of these models to high resolution Chandra observations of two polytropic clusters, MS 1137.5+6625 and CL J1226.9+3332, and two cool core clusters, Abell 1835 and Abell 2204. I show that the model accurately describes the spatially resolved spectroscopic and imaging data, including the cluster core region where significant cooling of the plasma is observed.;The optically thin hot (∼108 K) intra-cluster plasma is composed primarily of hydrogen (H) and helium (He) ions, with a small fraction (<1 %) of heavier elements, such as iron (Fe). A commonly adopted assumption is that He and other heavy elements are uniformly distributed throughout the intra-cluster medium (ICM), but theoretical studies suggest that the diffusion of He ions into the core of galaxy clusters --- Helium sedimentation --- can occur within a Hubble time.;The sedimentation of He ions within clusters of galaxies affects the physical quantities derived from X-ray observations, such as cluster gas mass and total mass, and the scaling relations between the X-ray mass proxy Y X and the total mass M. In this work, I also investigate the upper limits to the effect of He sedimentation on the measurement of cluster masses and the best-fit slopes of the YX-M 500 and YX -M2500 scaling relations using high signal to noise Chandra observations of ten galaxy clusters. |
