Astrophysics Colloquium: Galaxies: From Island Universes to Complex Ecosystems

Abstract: Our understanding of galaxies has evolved from viewing them as isolated stellar systems to recognizing them as dynamic, interconnected environments. Rather than simple collections of stars, galaxies are complex ecosystems of gas, dust, stars, and dark matter, regulated by continuous exchanges of energy, momentum, and metals through processes such as gas inflows, star formation, and feedback from stars and black holes.

Over the past few decades, advances in observations have transformed our view of how baryons and energy cycle through galaxies and their surroundings. In this talk, I will highlight key observational discoveries that have shaped our current picture of galactic ecosystems and discuss how they motivate the next generation of instrumentation and missions.