Galaxy Evolution in Dense Environments

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New telescope facilities and dedicated surveys have resulted in enormous progress in extra-galactic astronomy and cosmology over the past two decades. While we have now tightly constrained many of the fundamental cosmological parameters that describe our universe, there are still exciting unanswered questions concerning the formation and evolution of galaxies and larger structures. In my group we are interested in the evolution of galaxies and the connection between galaxies and their host environments. Many galaxies in the local universe do not live in isolation, but are clustered into systems called galaxy groups and clusters. In order to probe galaxy evolution in groups and clusters we will use a combination of multi-wavelength observations and state-of-the-art simulations. Galaxy populations are largely bimodal in their properties, with some galaxies being red and round and some galaxies being blue, star-forming, with disk-like shapes. There is evidence that over time galaxies transition from being blue and star-forming to red and passively evolving, but the precise mechanisms that drive this evolution are not well understood. Quenching is the process of shutting down star formation, which causes galaxies to transition from blue to red. We will study quenching by correlating observed galaxy properties with the properties of their host environment, including the host mass, host dynamical state, and the properties of X-ray gas that permeates groups and clusters. This proposal concentrates on three specific projects, which are an exciting new direction for us, because we combine cutting-edge observations and simulations to understand galaxy evolution in dense environments: 1) Study nearby and distant galaxy clusters with X-ray, optical and radio data to determine which quenching mechanisms are important at different epochs. 2) Using optical and radio data study the locations of quenching within individual galaxies and determine if quenching is dominated by internal or environmental processes for different galaxy populations. 3) Use simulations to study the dependence of galaxy evolution on the assembly history of their host halos. Through a combination of observations and simulations, we are ideally poised to understand the diverse ways in which galaxies evolve in different environments over cosmic time.