The first successful simultaneous observation of gravitational-wave and electromagnetic radiation from the neutron star merger GW170817 marked the advent of the era of multi-messenger astronomy. Parallel advances in gravitational-wave detectors and electromagnetic observing facilities will enable the astrophysics community to study in unprecedented detail compact object mergers and the host of exotic phenomena that accompany them. Of particular interest are the astrophysical origins of heavy elements produced through rapid neutron capture (r-process) nucleosynthesis. I will show how theoretical modeling of mergers’ electromagnetic “kilonova” counterparts provided the most conclusive evidence to date that merging neutron stars trigger r-process nucleosynthesis. I will also discuss how on-going and future work can clarify the role of these mergers in seeding the Universe with heavy elements, as well as constrain the importance of alternate potential sites of r-production. Finally, I will situate kilonovae in the context of radioactively-powered transients in general, and explain how the tools developed to study them can be applied to a continuum of explosive systems to elucidate the full range of astrophysical nucleosynthesis.
