Cracking the Most Luminous Supernovae: Multidimensional Simulations of Pulsational Pair-Instability Supernovae*

The extremely luminous supernovae such as SN 2006gy challenge the traditional view of core collapse supernovae, because they seem too luminous by more than one order of magnitude. Their unusual brightness might be explained by the collisions between shells of matter ejected by these massive stars at the end of their lives, so called pulsational pair-instability supernovae (PPSNe). We present the results from our multidimensional simulations of PPSNe with the state-of-the-art radiation-hydro code, CASTRO. We find significant amounts of fluid instabilities occurred during the shells apostrophe collisions and discuss how the resulting mixing affects the observational signature of PPSNe.