Special Universe Talk: The Origin of Spiral Patterns in Galaxies

by Jerry A. Sellwood (Rutgers University, USA)

Wednesday 8 Jun 2016, 11:00 → 12:00 Europe/Berlin

seminar room (Excellence Cluster Universe, Boltzmannstrasse 2, Garching)

We still do not have a satisfactory account of the origin of spiral patterns in galaxies. Some spiral patterns may be induced by tidal interaction, others appear to be driven by bars, but a more general mechanism is required to account for the ubiquity of the phenomenon. Linear stability studies of smooth disk galaxy models have led to a conundrum, yet simulations suggest that spiral patterns really are recurrent, gravitationally-driven, collective instabilities in the collisionless stellar fluid. Jerry will show that standing waves can be established in non-smooth disks and offer an explanation for a self-sustaining recurrence mechanism. There is some observational support for this picture.