White dwarf dynamical interactions and fast optical transients

Abstract

Recent advances in time-domain astronomy have uncovered a new class of optical transients with time-scales shorter than typical supernovae and a wide range of peak luminosities. Several subtypes have been identified within this broad class, including Ca-rich transients, Type Ia supernovae (SNe Ia) and fast/bright transients. We examine the predictions from a state-ofthe-art grid of three-dimensional simulations of dynamical white dwarf interactions in the context of these fast optical transients. We find that for collisions involving carbon oxygen or oxygen neon white dwarfs, the peak luminosities and durations of the light curves in our models are in good agreement with the properties of fast/bright transients. When one of the colliding white dwarfs is made of helium, the properties of the light curves are similar to those of Ca-rich gap transients. The model light curves from our white dwarf collisions are too slow to reproduce those of SNe Ia, and too fast to match any normal or peculiar SNe Ia.