Program: GN-2016A-FT-21

Chandra observations of the Type IIL supernova SN1970G obtained in 2011 showed a dramatic re-brightening in its X-ray luminosity. This sudden change contrasted starkly with radio emissions that have declined in strength throughout the supernova's lifetime and is consistent with the formation of a new pulsar wind nebula. Such a transformation has never been observed before and we request a modest investment of Gemini-N (+GMOS) time to obtain optical spectra that can uniquely test the reality of this interpretation. Specifically, we will look for broadening in the emission line profiles of the hydrogen- and oxygen-rich ejecta attributable to acceleration by the pulsar bubble. The results of our investigation will provide indispensable constraints on 1) supernova explosion mechanisms, 2) the pathways separating neutron star vs. black hole formation, and 3) binary population synthesis calculations.