The Photosphere Evolution, the Energy Sources, and the Early-time Excess of PTF11rka

Abstract In this paper, we determine the photosphere evolution of PTF11rka which is a type Ic supernova (SN) by fitting its spectral energy distributions at different epochs. We find that the photosphere of PTF11rka expanded at a constant velocity at early epochs, and the photosphere temperature increased slightly after reaching a minimum. These features are reminiscent of those of SN 2017dio. Based on the photosphere module that can describe the photosphere evolution of PTF11rka, we use the 56 Ni cascade decay model to fit its multiband light curves (LCs), finding that the model can well fit the photometric data. The derived ejecta mass and 56 Ni mass are respectively 8.76 M ⊙ and 0.29−0.41 M ⊙ ; the derived peak luminosity and the rise time of the theoretical bolometric LC of PTF11rka are ∼8.24 × 10 42 erg s −1 and ∼ 35 days, respectively. Moreover, we find that the theoretical multiband LCs and the theoretical bolometric LC of PTF11rka do not show early-time excesses proposed in the literature. This indicates that additional energy sources (e.g., the interaction between the ejecta and the circumstellar material) suggested to be responsible for the early-time excess can be neglected.