Clusters over Cosmic Time: ICM Evolution probed by Joint X-ray Observations

With deep gravitational potentials able to withstand the extreme mechanics of star formation and AGN activity, Galaxy Clusters serve as the ideal laboratories to study the history of feedback processes across cosmic time. The hot Intracluster Medium (ICM) provides a direct probe of the dynamic, thermodynamic, and chemical state of these systems. To fully understand the integrated feedback history of such massive objects, we require spatially resolved X-ray measurements of the ICM as a function of redshift, allowing us to quantify bulk evolution in addition to system-to-system scatter. Here we present detailed X-ray studies of 30+ galaxy clusters at 0.7 < z < 1.7 (including the ~20 most massive clusters discovered at z > 1) selected through Sunyaev-Zel’dovich (SZ) effect surveys and observed with both the XMM-Newton and Chandra satellites. For each cluster, we extract a precise gas mass profile and determine spatially resolved temperature and metallicity measurements. Our analysis provides the most precise measurement of the bulk metallicity of the ICM at high redshift (z > 1.25) to date. When combining our full sample with local Universe anchors, we reveal the first observational evidence for metallicity decreasing as we approach the epochs of peak star formation and AGN activity. Our high-redshift measurements of the thermodynamic profiles for these clusters exhibit remarkably small intrinsic scatter after scaling for redshift-dependent evolution, providing evidence for strong self-similarity in cluster evolution. This study demonstrates the power and the necessity of joint X-ray observations using our current flagships (Chandra + XMM-Newton) to study such faint, high-redshift systems, and provides crucial insight for the technical specifications of future X-ray missions to continue this work.