2020ApJ...891...98L

In this paper, we present the study of the energy reservoir powering the light curves (LCs) of PS1-12cil and SN 2012aa, which are superluminous and luminous supernovae (SNe), respectively. The multiband and bolometric LCs of these two SNe show unusual secondary bumps after the main peaks. The two-peaked LCs cannot be explained by any simple energy-source models (e.g., the ⁵⁶Ni cascade decay model, the magnetar spindown model, or the ejecta-circumstellar medium interaction model). Therefore, we employ the ⁵⁶Ni plus ejecta-circumstellar medium (CSM) interaction (CSI) model, the magnetar plus CSI model, and the double CSI model to fit their bolometric LCs, and find that both these two SNe can be explained by the double CSI model and the magnetar plus CSI model. Based on the modeling, we calculate the the time when the shells were expelled by the progenitors: provided that they were powered by double ejecta-shell CSI, the inner and outer shells might be expelled ∼0.2-3.6 and ∼2-25 yr before the explosions of the SNe, respectively; the shells were expelled ∼2-20 yr before the explosions of the SNe if they were powered by magnetars plus CSI.