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tokens: multiple power sources. Furthermore, the presence of H α emission lines in the late-time spectrum and the rebrightening in the late-time LC show an unambiguous signature for interactions between the SN ejecta and a hydrogen-rich CSM. Hence, any model with a single power source or double power sources is challenged in explaining the LC of iPTF13ehe. A triple-power-source model should be seriously considered. In this paper, we propose a triple-energy-source model for iPTF13ehe and try to understand its explosion mechanism and LC. This paper is organized as follows. In Sections 2 and 3 , we fit the early-time and late-time LC using double and triple-energy-source models, respectively. In Sections 4 and 5 , we discuss and conclude our results. 2. MODELING THE EARLY-TIME LC We start by studying the early LC and determining the power sources of iPTF13ehe. As pointed out by Yan et al. ( 2015 ), of 56 Ni were synthesized while of 56 Ni are required to account for the LC peak. Therefore, there should be other energy sources to aid the high peak luminosity of iPTF13ehe. The early-time spectra shows no H emission lines, indicating that the ejecta-CSM interaction can be neglected in the early-time luminosity evolution. Hence, the energy source aiding the SN might be a magnetar spin-down input. The possibility that iPTF13ehe is a CCSN and can be aided by a magnetar was also pointed out by Yan et al. ( 2015 ), though they did not provide further analysis. Considering the contribution from 56 Ni, which cannot be neglected, the most reasonable model should contain contributions from both 56 Ni and a magnetar. Wang et al. ( 2015b ) have constructed such a unified model for SNe Ic and explained three luminous SNe Ic. We employ this model here to fit the LC of iPTF13ehe. Supposing that the ratio of the r -band flux to bolometric flux remains nearly constant around the peak and in the late-time, we scale the r -band luminosities to obtain the bolometric luminosities. The scaled bolometric luminosities are rough, but they can be regarded as an approximation of real values. These data are plotted in Figure 1 . In this section, we use some models to fit the early-time LC. The photospheric velocity and the optical opacity κ are fixed to ∼13,000 km s −1 (Yan et al. 2015 ) and 0.2 cm −2 g −1 , respectively. Figure 1. Modeling iPTF13ehe’s early-time LC using 56 Ni, magnetar, and hybrid ( 56 Ni + magnetar) models. Data are obtained from Yan et al. ( 2015 ). The early-time and late-time bolometric luminosities scaled from r -band ones are shown as the orange filled circles and orange unfilled circles, respectively. The dashed–dotted line is the LC powered by 19 of 56 Ni; the dashed line is the LC powered by a magnetar; the solid line is the LC powered by 56 Ni and a magnetar. The short dashed line is the LC powered by 2.5 of 56 Ni with full trapping of gamma-rays. The other model parameter values are shown in the text. 2.1. <sup>56</sup>Ni Model The first of the models