Spectropolarimetry of Infant Supernovae

The explosion process of supernova is so dominant that the ejecta wipe out almost all traces of the pre-explosion configuration within a few days. Conventional photometry or spectroscopy provide limited information on the structures of the circumstellar medium as well as the SN ejecta themselves, projected and smeared into the single dimension of radial velocity. Critical information about the interaction of the ejecta with a companion and any circumstellar matter is encoded in the geometry of the explosion, which cannot be spatially resolved, can only be probed with polarimetry. I will present our recent VLT spectropolarimetry observations of young Type Ia supernova and how it constrains the explosion mechanisms. Lessons from infant core-collapse supernova spectropolarimetry will also be discussed.