Interacting Supernovae: Spectra and Light Curves

Abstract

The ejecta of a supernova explosion expand with a very high velocity and they immediately impact the circumstellar material. The manifestation of this impact depends mainly on the density of the circumstellar material and on the velocity contrast between the ejecta and that material. We describe the effects of the interaction of supernova ejecta with circumstellar material on the observed spectral features and light curves of supernovae. The most interesting effect of the interaction is the powerful production of light by radiating shock waves. Many superluminous supernovae may be explained by this mechanism. We describe the relevant physical picture for the efficient production of light in those objects, which is most effective when the mass of circumstellar material is large and slowly moving.