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The Galactic Ecosystem: connecting internal structure with formation history

Dr. Rachel Somerville Rutgers University The Galactic Ecosystem: connecting internal structure with formation history It has long been known that galaxies' internal structure is connected with their star formation activity in the nearby universe. Recent surveys have allowed us to study these correlations out to very large distances, allowing us for the first time to quantify these relationships over a significant span of cosmic time for statistically robust samples of objects. It has been known for several years that galaxies are growing in mass and radius, experiencing morphological transformation, and "downsizing" their star formation activity over cosmic time. Now, new observations are painting a picture in which the internal structure of galaxies (size and morphology) is intimately linked with their star formation activity and formation history. There are hints that the co-evolution of supermassive black holes with their host galaxies may be the driving force behind these correlations, but this remains controversial. While cosmological simulations set within the hierarchical formation scenario of Cold Dark Matter currently offer a plausible story for interpreting these observations, many puzzles remain. I will review recent insights gleaned from deep multi-wavelength surveys and state-of-the-art theoretical models and simulations, as well as highlight the open questions and challenges for the future.