Magnetized outflows from protomagnetars as the sources of heavy nuclei and multi-messenger emission

Nuclei heavier than iron are likely to be produced via rapid neutron capture process (r-process) in magnetized outflows from explosive events including compact mergers and core-collapse supernovae. In this talk, I will discuss the potential of these neutron-rich environments for r-process nucleosynthesis and present a comparative analysis of nucleosynthesis yields from these source classes. As the decay of unstable r-process nuclei can power kilonova emission in UVOIR bands, we estimate the likelihood of their joint detection with accompanying GW signal in the ongoing LVK observing run. In addition to examining the acceleration and survival conditions for these nuclei that is relevant for the production of ultra-high energy cosmic rays, we study the propagation of these outflows in Wolf-Rayet stars as well as extended stellar progenitors such as blue/red supergiants. We analyze the criteria for successful breakout of the jet and show that high-energy neutrinos can be produced for the extended progenitors. These high-energy neutrinos will be detectable from cosmological distances with upcoming facilities such as IceCube-Gen2.