Radiation Transport Modeling of Kilonovae and Broad-lined Ic Supernovae

This thesis presents models of the radiative signatures of two unusual electromagnetic transients: radioactive transients ("kilonovae") associated with the merger of a neutron star with a second neutron star or a black hole, and broad-lined Type Ic supernovae. The first portion of the thesis focuses on improving inputs for radiation transport simulations of kilonovae. I first address opacity. I present new calculations of the opacities of elements synthesized in the kilonova ejecta, and carry out radiation transport simulations of kilonovae using these new opacities. Next, I develop detailed models of the radioactive heating of the kilonova ejecta and explore its effects on kilonova light curves. These two projects advanced our understanding of the expected emission from kilonovae, and will inform efforts to find and analyze these elusive transients. The final part of this thesis considers broad-lined Ic supernovae. I use multidimensional hydrodynamical and radiation transport simulations to investigate the validity of the single-engine model for broad-lined superonva Ic/gamma-ray burst systems. I demonstrate that a jet engine injected into a stripped-envelope progenitor star can produce both a supernova with broad spectral features and a long-duration gamma-ray burst