R-process nucleosynthesis in neutron star mergers and collapsars featuring Dan Siegel

Dan Siegel from Columbia University gives a talk.

Title: R-process nucleosynthesis in neutron star mergers and collapsars

Abstract: Combining the kilonova observations of the neutron-star merger GW170817 and general-relativistic magnetohydrodynamic simulations, I will argue that the rapid neutron-capture (r-process) elements synthesized in GW170817 originate from powerful outflows of a post-merger accretion disk. Similar accretion flows are expected following the collapse of rapidly rotating massive stars ('collapsars') that are thought to power long gamma-ray bursts. Based on recent progress in our understanding of the evolution of both neutron-star mergers and collapsars, I will confront first-principle theoretical predictions with observations of r-process enrichment, and argue that collapsars are likely the dominant source of heavy r-process elements in the Milky Way. In particular, enrichment through collapsars appears to solve a number of problems related to r-process abundances in stars of the Milky Way disk and the halo, as well as in dwarf galaxies and globular clusters. I will also discuss how future multimessenger observations can help to directly probe or constrain r-process nucleosynthesis in collapsars.