Signatures of heavy element nucleosynthesis in transients

The astrophysical sources where heavy elements are synthesized are not fully understood and are windows into a rich array of high-energy astrophysics. We model and compare these astrophysical sources, such as the outflows of protomagnetars and compact object mergers, and make detailed predictions for the nucleosynthesis distributions from such sites. We also make estimates for the signatures of heavy element synthesis. We find that protomagnetars can synthesize moderately heavy nuclei and are compelling sources of ultra-high-energy cosmic rays after acceleration. We also find that compact object mergers, like binary neutron star and black hole-neutron star mergers, can undergo a robust r-process and source detectable kilonovae.