Exploring Dynamical Ejecta in Black Hole-Neutron Star Binaries: Neutron Star Disruption and a Dual Potential for Kilonovae and Compact Binary Gamma-Ray Bursts

Merging black hole–neutron star (BHNS) binaries serve as an important production mechanism in the creation of gravitational waves (GWs) and are also a proposed origin of UV/optical/infrared kilonova signals and gamma-ray bursts (GRBs). For a BHNS merger to produce one of these electromagnetic (EM) transients, the spin of the black hole must be sufficiently high, creating a tidal field strong enough to disrupt the neutron star. With spins higher than this threshold, a disrupting BHNS binary may eject a few percent of a solar mass of matter, leading to observable kilonovae driven by radioactive decays in the ejecta, and/or a compact-binary GRB (cbGRB) resulting from the formation of a massive, hot accretion disk. In this talk, I summarize new and updated results from simulations of BHNS binaries with black hole spins above the predicted spin limit for disruption. These simulations serve as an exploration into the behavior of dynamical ejecta close to this disruption threshold using the Spectral Einstein Code (SpEC) for binaries described by SFHo and DD2 equations of state.