Galaxy clusters are the largest gravitationally bound structures in the universe and, therefore, are potent cosmological probes. Perhaps surprisingly, their baryonic (and observable) matter is principally in the hot, diffuse plasma located between the galaxies, i.e., the intracluster medium, not in luminous matter like stars. This intracluster medium is composed of thermal and nonthermal components. The thermal gas undergoes both cooling and heating (via feedback from supernovae and active galactic nuclei) in the central regions. The nonthermal component consists of cosmic rays, generated via shocks and active galactic nuclei, and magnetic fields.
Despite their importance, the nonthermal constituents have received relatively little study in part because of the challenges in the numerical modeling needed to follow the relevant physics. In an effort to begin to close this gap in our understanding of galaxy cluster environments, Dr. Burns and collaborators will apply their recently developed adaptive mesh refinement magnetohydrodynamic N-body code to the problem. Most notably, this new tool is capable of evolving both cosmic rays and magnetic fields in the large-scale cosmological environment. Here it will be employed to simulate both thermal and nonthermal processes within galaxy clusters. These simulations will iterated upon until convergence is achieved with a combination of thermal and nonthermal physics that best reproduces available observations.
Postdoctoral fellows and graduate students will be trained through active participation in all aspects of this work. The data from these simulations and the tools for converting the outputs into standard observational formats will be made available to the astronomical and broader community through an on-line archive. Dr. Burns and collaborators will also construct course modules showing concepts of cosmological gas and N-body particle dynamics via their numerical simulations for classes ranging from introductory astronomy to graduate astrophysics. These visualizations will also be developed into new planetarium shows.
