Triangle Nuclear Theory Colloquium - Neutron star mergers as a laboratory for neutrino physics: neutrino oscillations, neutrino-matter interactions, and neutrino advection

The 2017 detection of the in-spiral and merger of two neutron stars was a landmark discovery in astrophysics. Through a wealth of multi-messenger data, we now know that the merger of these ultracompact stellar remnants is a central engine of short gamma ray bursts and a site of r-process nucleosynthesis, where the heaviest elements in our universe are formed. The radioactive decay of unstable heavy elements produced in such mergers powers an optical and infra-red transient: The kilonova.

These merger events and their aftermath depend sensitively on the behavior of neutrinos, which control the abundance of free neutrons available for the r-process. In this talk, I discuss how and why this problem is a significant modeling challenge for the community and present high-fidelity simulations of post-neutron star merger disks, and discuss the impacts of various processes, including the neutrino fast-flavor instability, on observables, such as kilonova and nucleosynthetic yields.