Exploring the Energy Sources Powering the Light Curve of the Type Ibn Supernova PS15dpn and the Mass-Loss History of the SN Progenitor

PS15dpn is a luminous rapidly rising Type Ibn supernova (SN) discovered by Pan-STARRS1 (PS1). Previous study showed that its bolometric light curve (LC) cannot be explained by the $^{56}$Ni model. In this paper, we used the $^{56}$Ni model, the magnetar model, the circumstellar interaction (CSI) model, and the CSI plus $^{56}$Ni model to fit the bolometric LC of PS15dpn. We found that the $^{56}$Ni model can fit the bolometric LC but the parameters are unrealistic, and that the magnetar model, the CSI model, and the CSI plus $^{56}$Ni model can match the data with reasonable parameters. Considering the facts that the emission lines indicative of the interaction between the ejecta and the CSM have been confirmed, and that the SNe produced by the explosions of massive stars can synthesize moderate amount of $^{56}$Ni, we suggest that the CSI plus $^{56}$Ni model is the most promising. Assuming that the CSM is a shell (wind), the masses of the ejecta, the CSM, and the $^{56}$Ni are $15.79_{-4.77}^{+5.44}$ M$_\odot$ ($14.18_{-1.64}^{+1.81}$ M$_\odot$), $0.84_{-0.10}^{+0.13}$ M$_\odot$ ($0.88_{-0.12}^{+0.11}$ M$_\odot$), and $0.32_{-0.11}^{+0.11}$ M$_\odot$ ($0.16_{-0.08}^{+0.13}$ M$_\odot$), respectively. The inferred ejecta masses are consistent with the scenario that the progenitors of SNe Ibn are massive Wolf-Rayet stars. Adopting the shell CSM scenario, the shell might be expelled by an eruption of the progenitor just $\sim$ 17$-$167 days prior to the SN explosion; for the wind scenario, the inferred mass-loss rate of the wind is $\sim 8.0$ M$_\odot$ yr$^{-1}$, indicating that the wind is a "super-wind" having extreme high mass-loss rate.

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