The formation and evolution of intracluster light: Simulations and observations

This dissertation presents a series of studies of the intracluster light, or ICL, in galaxy clusters. The ICL consists of stellar luminosity within the cluster that resides outside of the individual cluster galaxies, and is characterized by its very low surface brightness. The aim of this dissertation is to identify the mechanisms through which the ICL is generated, and to relate its observable properties to the broader dynamical evolution of the cluster and its constituent galaxies. Several of the studies in this dissertation are based on N-body simulations of the evolution of galaxy clusters, which are specifically designed to track the dynamics of the ICL component. With these simulations I show that ICL is generated through the gravitational stripping which occurs as galaxies and groups within the cluster interact with one another. Thus, the quantity of ICL increases as the cluster evolves, and its properties are intimately related to the specific dynamical history of the cluster. I also find that the morphology of the ICL evolves as the cluster ages dynamically, where the discrete streams and substructures which dominate early in the cluster's history dissolve to form a diffuse, amorphous background at later times. Additionally, while there is no single universally accepted quantitative definition of what constitutes the ICL, I find that most commonly used definitions probe the cluster's evolution similarly. Finally, I present a deep imaging study of the ICL in the core of the Virgo cluster. I show that the discrete tidal features surrounding M87, the cluster's cD galaxy, which are very likely the result of low-mass galaxies being stripped through interactions with the cD, have colors similar to both the extended cD envelope and the more diffuse ICL component within the cluster. This suggests a common origin for all three types of feature, where the cD envelope and the diffuse ICL are generated from the dissolution of the streams created by the gravitational stripping of low-mass galaxies within the cluster.