Institute for Advanced Study/Princeton University Joint Astrophysics Colloquium

The first light of a core-collapse supernova emerges the moment a shock front breaches the stellar photosphere — just after the star has been engulfed by its explosion, and just before it releases its fastest ejecta. Shock emergence is implicated in several types of transients, including low-luminosity gamma-ray bursts and fast-evolving explosions found in the optical. Some of these events require this phenomenon to divert an unusually large fraction of the explosion energy toward the stellar surface. This raises the question: how can a given stellar mass and explosion energy be distributed to yield the most spectacular shock breakout? I will address this question for both spherical and non-spherical explosions, and identify several scenarios in which real events might be especially dramatic. For non-spherical explosions the development of strong, non-radial motion provides an unexpected dividend, a new source for transient emission.