Johnny Tsao Final Defense

Numerical relativity combines general relativity with relativistic hydrodynamics to model compact objects such as black holes and neutron stars. Using MAYA, a local version of the Einstein Toolkit, this work investigates the effects of neutron star compactness and orbital eccentricity on neutron star–black hole mergers, gravitational-wave signals, and matter ejection. In addition to these applications, radiation-fluid and neutrino-transport techniques are developed to incorporate radiation physics into numerical relativity. Radiation fluids are modeled as self-gravitating fluids to study dynamical instability of photon stars, and neutrino transport is explored through moment-based methods by adapting existing M1 algorithms to the infrastructure-agnostic GRHayL library.