Nucleosynthesis and observational evidences of magneto rotational driven supernovae

Mortiz Reichert

TU Darmstadt

Abstract: About half of the heavy elements in our Universe are synthesized by one process, the rapid neutron capture process (r-process). This process requires extreme and violent environments that achieve the necessary neutron-rich conditions. Neutron star mergers and magneto rotational driven supernovae are promising candidates to host the r-process. We investigate the r-process from an observational as well as a nucleosynthesis point of view. Our ultimate goal is to find out indications in favor of, or against neutron star mergers being the proposed only source of r-process elements. Therefore, we are particularly interested in the chemical evolution of heavy elements. Stars that are embedded in the environment of dwarf galaxies provide a perfect stellar laboratory, since they are usually well separated and shielded from external pollution and each galaxy has its own chemical history. We study 380 stars from 13 dwarf galaxies and derive abundances for 12 elements. To learn about the enrichment in heavy elements of dwarf galaxies, we first examine their individual chemical histories to ultimately learn about the heavy element enrichment of dwarf galaxies. Events that may fulfill all found abundance trends are magneto rotational driven supernovae. We use a modern state of the art hydrodynamical simulation to investigate the synthesis of elements in this type of event. In total, we calculate the nucleosynthesis of four models with different magnetic field strengths and rotation rates. We find elements up to xenon (second r-process peak) for the model with weakest magnetic field strength, which is caused by a late change of the proto-neutron star morphology. For the model with the strongest magnetic field strength, we find a fully operating r-process. Having a detailed abundance pattern of this event calculated, we discuss possible observables.