Relativistic Explosions Across the Universe

Jets are a ubiquitous phenomena in astrophysics — spanning a remarkable range in size, velocity, and energy output. But only a handful of systems are capable of accelerating ejecta to speeds approaching that of light — the best known examples of such relativistic jets are blazars and gamma-ray bursts. Here I describe recent efforts to characterize the properties of known classes of systems with relativistic jets — in particular gamma-ray bursts from both the core-collapse of massive stars as well as the merger of binary neutron stars. I will also highlight attempts to uncover new classes of relativistic ejecta, specifically evidence for such high-velocity outflows from tidal disruption events, and searches for “orphan” gamma-ray burst afterglows. Along the way, I’ll highlight the critical role in these efforts played by two facilities, the Neil Gehrels Swift Observatory and the Zwicky Transient Facility.