Modeling the Light Curve of the Transient Scp06f6

We consider simple models based on core collapse or pair-formation supernovae to account for the light curve of the transient SCP06F6. A radioactive decay diffusion model provides estimates of the mass of the required radioactive nickel and the ejecta as functions of the unknown redshift. An opacity change such as by dust formation or a recombination front may account for the rapid decline from maximum. Within this class of model, the redshift must be less than z ∼ 1 or the nickel mass would exceed the total mass of the ejecta, the radiated energy would exceed the kinetic energy and kinematic and photometric estimates of the radius would disagree. We particularly investigate two specific redshifts: z = 0.143, for which Gaensicke et al. (2008) have proposed that the unidentified broad absorption features in the spectrum of SCP06F6 are C2 Swan bands, and z = 0.57 based on a crude agreement with the Ca H&K and UV ironpeak absorption features that are characteristic of supernovae of various types. For the lower redshift, we obtain a nickel mass of 0.3 M ⊙ and an ejected envelope mass of ∼ 38 M⊙, while for the latter case we find 4.8 M ⊙ and 20 M⊙, respectively, for fiducial parameters. The kinetic energy of the ejecta, while dependent on uncertain parameters, is generally large, ∼ 10 52 erg, throughout this range of redshift. The ejected masses and kinetic energies are smaller for a more tightly constrained model invoking envelope recombination. We also discuss the possibilities of circumstellar matter (CSM) shell diffusion and shock interaction models. In general, optically-thick CSM diffusion models can fit the data with the underlying energy coming from an energetic buried supernova. Models in which the CSM is of lower density so that the shock energy is both rapidly thermalized and radiated tend not to be self-consistent. We suggest that a model of SCP06F6 worth futher exploration is one in which the redshift is