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

Abstract

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 = 0.69 +/- 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_V = -19.74 and the production of ~ 1.2 M_sun of 56Ni. This suggests a super-Chandrasekhar mass progenitor. A double degenerate merger is consistent with these observations.

Accepted for publication in ApJL (5 pages, 4 figures). UBVr'i' light curves, UVOIR light curves, and spectra available at http://www.cfa.harvard.edu/supernova/SN2006gz