The light curves and spectra of supernova explosions: multi-dimensional time-dependent Monte Carlo radiative transfer calculations

While the disruption of a star in a supernova explosion lasts only seconds, the ejected stellar material, much of it newly radioactive, continues to shine brightly for several months. Multi-physics simulations of supernova are now illuminating the physics of the stellar explosion itself, but further post-processing of models with a radiative transfer code is needed to predict the visible emission and compare directly to astronomical observations. Here we discuss Monte Carlo techniques for addressing multi-group time-dependent radiative transfer in 3-dimensional, rapidly expanding atmospheres. We have developed the SEDONA code, which calculates detailed angle dependent light curves, spectra, and polarization, and have applied it to study the nature and cosmological utility of supernovae. The code is scalable and is typically run on high-performance computers using 1024 processors.