Institute for Advanced Study/Princeton University Joint Astrophysics Colloquium

Nature's two magnificent explosions, long-duration gamma-ray bursts (GRBs) and stripped-envelope supernovae (SNe), are both products of collapsing massive stars. Yet, over the last 15 years, we have not determined the detailed make-up of the stellar progenitors of each kind of explosion, nor the conditions that lead to each kind of explosion in massive stripped stars. While long-duration GRBs emit relativistic jets of high-energy radiation, stripped SNe are core-collapse explosions whose massive progenitors have been stripped of their outer hydrogen and helium envelopes. Understanding the progenitors of different kinds of explosions impacts many fields of astrophysics, including using them as cosmological tools. I will present a number of comprehensive observational studies that probe the progenitor environments, their metallicities and the explosion parameters of SNe with and without GRBs, as well as those of normal Stripped SNe, with the goal of constraining their progenitor systems and explosions mechanisms. I will conclude with an outlook on how the most promising venues of research - using the many existing and upcoming innovative surveys such as the Palomar Transient Factory and LSST - have shed new light on the diverse deaths of massive stars, and will continue to do so.