Evolution of the Thermodynamic Properties of Clusters of Galaxies out to Redshift of 1.8

Abstract

<jats:title>Abstract</jats:title> <jats:p>The thermodynamic properties of the hot plasma in galaxy clusters retain information on the processes leading to the formation and evolution of the gas in their deep, dark matter potential wells. These processes are dictated not only by gravity but also by gas physics, e.g., active galactic nucleus feedback and turbulence. In this work, we study the thermodynamic properties, e.g., density, temperature, pressure, and entropy, of the most massive and the most distant (seven clusters at <jats:italic>z</jats:italic> &gt; 1.2) clusters selected by the South Pole Telescope and compare them with those of the nearby clusters (13 clusters at <jats:italic>z</jats:italic> &lt; 0.1) to constrain their evolution as a function of time and radius. We find that thermodynamic properties in the outskirts of high-redshift clusters are remarkably similar to the low-redshift clusters, and their evolution follows the prediction of the self-similar model. Their intrinsic scatter is larger, indicating that the physical properties that lead to the formation and virialization of cluster outskirts show evolving variance. On the other hand, thermodynamic properties in the cluster cores deviate significantly from self-similarity, indicating that the processes that regulate the core are already in place in these very high redshift clusters. This result is supported by the unevolving physical scatter of all thermodynamic quantities in cluster cores.</jats:p>