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(15)(B) = 0.69 +/- 0.04]. The early-time Si II velocity is low, 15 implying it was slowed by an envelope of unburned material. Our best estimate of the luminosity implies M-v = -19.74 and the production of similar to 1.2 M-circle dot of Ni-56. This suggests a super-Chandrasekhar mass progenitor. A double degenerate merger is consistent with these observations.