Speaker
Description
As young children explore the world around them, they quickly discover that a lot can be learned about a complex system by gently poking it and observing how it reacts to that. Astronomers who are interested in the internal workings of disk galaxies, such as our Milky Way, also follow this approach. In this case, nature does the poking for us. The stellar and gaseous disks of galaxies are continuously perturbed by orbiting globular clusters and dark-matter substructures, molecular clouds, the graininess of the stellar density distribution, stellar feedback, encounters with other galaxies, etc. Galactic disks respond to these perturbations by developing spiral-shaped patterns, composed of a spectrum of growing and damped eigenmodes. In this talk, I review my work of the last few years (Fiteni, De Rijcke, Debattista, Caruana 2024; De Rijcke, Fouvry, Pichon 2019; De Rijcke, Fouvry, Dehnen 2019, De Rijcke & Voulis 2016), aimed at gaining insights into the intricate dynamics underlying the spiral patterns of disk galaxies. I show how dynamical theory is a powerful tool that has the unique ability to help us understand the properties (morphology, kinematics, lifespan, ...) of spiral patterns observed in N-body simulations (a crucial first step towards understanding spirals in real galaxies). I highlight the surprisingly important role played by weakly damped modes in driving the secular evolution of galaxies.
