Radio Supernovae: Circum-Stellar Investigation (C.S.I.) of Supernova Progenitor Stars

Prior to explosion, a supernova progenitor slowly loses significant amounts of its hydrogen envelope in a stellar wind. After the explosion, the blastwave interacts with this wind producing synchrotron emission. A year of radio observations allows us to probe the progenitor evolution for a thousand years. The EVLA and SKA would represent more than an order of magnitude improvement in our ability to explore the pre-explosion lives of a significantly large population of supernova progenitor stars. It will allow us to move beyond the crude optical classifications and develop a deeper physical understanding of how massive stars live and die.