An attractor for the dynamical state of the intracluster medium

Galaxy clusters provide us with important information about the cosmology of our universe. Observations of the X-ray radiation or of the Sunyaev-Zel'dovich effect allow us to measure the density and temperature of the hot intergalactic medium between the galaxies in a cluster, which then allow us to calculate the total mass of the galaxy cluster. However, no simple connection between the density and the temperature profiles has been identified. Here, we use controlled high-resolution numerical simulations to identify a relation between the density and temperature of the gas in equilibrated galaxy clusters. We demonstrate that the temperature-density relation is a real attractor, by showing that a wide range of equilibrated structures all move toward the attractor when perturbed and subsequently allowed to relax. For structures that have undergone sufficient perturbations for this connection to hold, one can therefore extract the mass profile directly from the X-ray intensity profile.