The Luminous and Carbon-rich Supernova 2006gz: A Double Degenerate Merger?

Spectra and light curves of SN 2006gz show the strongest signature of unburned carbon and one of the slowest fading light curves ever seen in a Type Ia event [ Delta m sub(15)(B) = 0.69 plus or minus 0.04]. The early-time Si II velocity is low, implying it was slowed by an envelope of unburned material. Our best estimate of the luminosity implies M sub(v) = -19.74 and the production of similar to 1.2 M [unk] of super(56)Ni. This suggests a super-Chandrasekhar mass progenitor. A double degenerate merger is consistent with these observations.