Neutron-star mergers and r-process nucleosynthesis

Gravitational-wave detectors have transformed the way we observe the Universe. Together with ground and space-based electromagnetic observatories, they have provided key insights into the long-standing question of how the heavy elements in the periodic table are synthesized. I will discuss recent results from simulations of neutron-star mergers with an emphasis on post-merger physics and electromagnetic observables. In particular, I will discuss recent results at the interface of numerical relativity and nuclear astrophysics, formulate a conjecture regarding the main r-process production site, highlight some recent ideas on applications of these concepts in other astrophysical systems, and point out how multi-messenger astronomy can lead to the answer of a >70-year old fundamental question: How does the Universe create the heaviest elements?