The Universe's Most Extreme Explosions Across Cosmic History
Dan Perley

Massive stars have been known to end their lives violently for almost a century, but the extrema of this process have been appreciated only recently: rare classes of "superluminous" supernovae are hundreds of times more luminous than other SNe, and long-duration gamma-ray bursts fleetingly outshine the brightest quasars by orders of magnitude. Their immense luminosities make these events easily detectable from great distances, from which they can serve as probes of the high-redshift IGM, ISM, and perhaps the rate and sites of cosmic star-formation. However, employing them as tools in this way requires a thorough understanding of how varying conditions (e.g. varying metallicity) may favor or disfavor their production in different environments. I will discuss two large surveys I am leading to study the connection between extreme transients and their galaxy environments: SHOALS, a multi-observatory effort to examine the impact of galaxy evolution on the GRB rate and host population across cosmic history, as well as the PTF superluminous-supernova host project at Keck and Palomar. GRBs and one class of SLSNe are heavily suppressed in Solar-metallicity galaxies but may be enhanced in the most active starbursts. Extreme transients will be discovered at a wider range of distances and in much greater numbers in the coming era of all-sky synoptic surveys, and will prove useful for understanding the composition and evolution of dwarf galaxies, the history of the universe, and theories of massive-stellar evolution and variations in the IMF.