Abstract
Stripped-envelope (SE) supernovae (SNe) include H-poor (Type IIb), H-free (Type Ib), and He-free (Type Ic) events thought to be associated with the deaths of massive stars. The exact nature of their progenitors is a matter of debate with several lines of evidence pointing towards intermediate mass (Minit< 20 M⊙) stars in binary systems, while in other cases they may be linked to single massive Wolf-Rayet stars. Here we present the analysis of the light curves of 34 SE SNe published by the Carnegie Supernova Project (CSP-I) that are unparalleled in terms of photometric accuracy and wavelength range. Light-curve parameters are estimated through the fits of an analytical function and trends are searched for among the resulting fit parameters. Detailed inspection of the dataset suggests a tentative correlation between the peak absolute B-band magnitude and Δm15(B), while the post maximum light curves reveals a correlation between the late-time linear slope and Δm15. Making use of the full set of optical and near-IR photometry, combined with robust host-galaxy extinction corrections, comprehensive bolometric light curves are constructed and compared to both analytic and hydrodynamical models. This analysis finds consistent results among the two different modeling techniques and from the hydrodynamical models we obtained ejecta masses of 1.1–6.2M⊙, 56Ni masses of 0.03–0.35M⊙, and explosion energies (excluding two SNe Ic-BL) of 0.25–3.0 × 1051 erg. Our analysis indicates that adopting κ = 0.07 cm2 g-1 as the mean opacity serves to be a suitable assumption when comparing Arnett-model results to those obtained from hydrodynamical calculations. We also find that adopting He i and O i line velocities to infer the expansion velocity in He-rich and He-poor SNe, respectively, provides ejecta masses relatively similar to those obtained by using the Fe ii line velocities, although the use of Fe ii as a diagnostic does imply higher explosion energies. The inferred range of ejecta masses are compatible with intermediate mass (MZAMS ≤ 20M⊙) progenitor stars in binary systems for the majority of SE SNe. Furthermore, our hydrodynamical modeling of the bolometric light curves suggests a significant fraction of the sample may have experienced significant mixing of 56Ni, particularly in the case of SNe Ic.
Highlights
Stripped-envelope (SE) core-collapse supernovae (SNe) are associated with the deaths of massive stars that have experienced significant mass loss over their evolutionary lifetimes
Upon comparison of the other key explosion parameters derived from the Arnett and hydrodynamical models, as shown in Fig. 24, we find that 56Ni masses, Mej, and EK are in good agreement, with the Arnett models providing slightly larger ejecta masses and kinetic energies for three objects
We presented the analysis of a sample of 34 SE SNe from the CSP-I
Summary
Stripped-envelope (SE) core-collapse supernovae (SNe) are associated with the deaths of massive stars that have experienced significant mass loss over their evolutionary lifetimes. Mass constraints of SE SN progenitors obtained from oxygen-abundance determinations by modeling late-phase spectroscopy point towards progenitors characterized by MZAMS ≈ 12–13 M (see, e.g., Jerkstrand et al 2015) This is corroborated by the lack of detections of bright Wolf-Rayet (WR) stars in pre-explosion images of nearby SE SNe (Eldridge et al 2013), as well as by the relatively high rate of SE SNe (Smith et al 2011; Shivvers et al 2017). A few SE SNe with large ejecta masses (corresponding to broad light curves) have been suggested, such as SN 2005bf (e.g., Folatelli et al 2006), SN 2011bm (Valenti et al 2012), iPTF15dtg (Taddia et al 2016), PTF11mnb (Taddia et al 2018), and SN 2012aa (Roy et al 2016) These objects could have possibly arisen from massive (MZAMS > 30 M ) single stars.
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