2018ApJ...856...59L

In this paper, we investigate two hydrogen-poor superluminous supernovae (SLSNe), iPTF15esb and iPTF13dcc, whose light curves (LCs) show significant deviation from the smooth rise and fall. The LC of iPTF15esb exhibits two peaks and a post-peak plateau, and furthermore the late-time spectrum of iPTF15esb shows a strong, broad Hα emission line. The early-time LC of iPTF13dcc shows a long-duration bump followed by the second peak. Here, we propose an ejecta-circumstellar medium interaction model involving multiple shells/winds and use it to explain the LCs of iPTF15esb and iPTF13dcc. We find that the theoretical LCs reproduced by this model can match observations of iPTF15esb and iPTF13dcc. Based on our results, we infer that the progenitors have undergone multiple violent mass-loss processes before the SN explosion. In addition, we find that the variation trend of our inferred densities of the shells is consistent with that predicted by the stellar mass-loss history before an SN explosion. Further investigations for other bumpy SLSNe/SNe would shed light on their nature and provide a probe for the mass-loss history of their progenitors.