Kilonovae: Explosive Origins of the Universe's Heavy Elements

Synopsis

Throughout history, humans have coveted the universe's heavy elements, like silver and gold, while modern technology has made others (like uranium) even more important. In nature, many of these elements can only be produced in extremely hot environments where free neutrons vastly outnumber protons; the violently ejected material from a neutron star merger event is thought to provide just the right conditions. All these hot, heavy elements glow brightly enough to be measured in the visible or near-infrared for a few days to weeks after the merger. This type of transient astronomical event (a "kilonova") was observed for the first time in 2017 following the detection of gravitational waves (GWs) from a neutron star merger. More kilonovae are expected to be found after future GW detections, yielding a wealth of information about the heavy elements that were produced. In this presentation, I will give an overview of these kilonovae: the theory behind them, their observation, and the information they encode about the origin of heavy elements in our universe.