Slowly Breaking Waves: The Longevity of Tidally Induced Spiral Structure
|Date/Time:||Friday, 15 Apr 2011 from 4:10 pm to 5:00 pm|
|Location:||Room 3 Physics|
We have discovered surprisingly long-lived waves in two sets of numerical models of fast (marginally bound or unbound) flyby galaxy collisions. Although there is variation in the appearance of the waves with time, they do not disappear and reform recurrently, as seen in other cases described in the literature. We also present an analytic theory that can account for the wave structure, suggesting that they are caustic waves in ensembles of stars pursuing correlated epicyclic orbits after the disturbance. The models suggest that this type of wave may persist for a couple of Gyr, and that this mechanism may be well represented in observed spirals. This effect may be one of several processes that contribute to galaxy harassment, or to producing the Butcher-Oemler effect.