On the Road to More Realistic Galaxy Cluster Simulations: The Effects of Radiative Cooling and Thermal Feedback Prescriptions on the Observational Properties of Simulated Galaxy Clusters

Flux-limited X-ray surveys of galaxy clusters show that clusters come in two roughly equally proportioned varieties: "cool core" clusters (CCs) and non-"cool core" clusters (NCCs). In previous work, we have demonstrated using cosmological N-body + Eulerian hydrodynamic simulations that NCCs are often consistent with early major merger events that destroy embryonic CCs. In this paper we extend those results and conduct a series of simulations using different methods of gas cooling and of energy and metal feedback from supernovae, where we attempt to produce a population of clusters with realistic central cooling times, entropies, and temperatures. We find that the use of metallicity-dependent gas cooling is essential to prevent early overcooling, and that adjusting the amount of energy and metal feedback can have a significant impact on observable X-ray quantities of the gas. We are able to produce clusters with more realistic central observable quantities than have previously been attained. However, there are still significant discrepancies between the simulated clusters and observations, which indicates that a different approach to simulating galaxies in clusters is needed. We conclude by looking toward a promising subgrid method of modeling galaxy feedback in clusters that may help to ameliorate the discrepancies between simulations and observations.