The Carnegie Supernova Project I

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), which 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 ∆m15(B), while the post maximum light curves reveals a correlation between the late-time linear slope and ∆m15. 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 − 6.2 M⊙, 56 Ni masses of 0.03 − 0.35 M⊙, and explosion energies (excluding two SNe Ic-BL) of 0.25 − 3.0 × 10 51 erg. Our analysis indicates that adopting κ = 0.07 cm 2 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 ≤ 20 M ⊙ ) progenitor stars in binary systems for the majority of SE SNe. Furthermore, our hydrodynamical modeling of the bolometric light curves suggest a significant fraction of the sample may have experienced significant mixing of 56 Ni, particularly in the case of SNe Ic.

Constraining the Final Fates of Massive Stars by Oxygen and Iron Enrichment History in the Galaxy

“…It is worth comparing this constraint with the ejecta mass indicated by observations of type Ibc SNe. Recent observational studies of stripped envelope SNe found an average ejecta mass of ∼ 2-3 M and 56 Ni mass of ∼ 0.2 M for type Ib and Ic SNe (Drout et al 2011;Lyman et al 2016;Taddia et al 2017). This oxygen mass constraint already exceeds the average ejecta mass implied by observations.…”

The Carnegie Supernova Project I

“…For those objects with observations beginning past maximum, an estimate of the time of B-band maximum was obtained using the relation of Fig. 3 from Taddia et al (2018). The relation correlates the time of B-band maximum to the time of maximum of the other passbands, all of which except the u band peak at phases after the time of B-band maximum.…”

“…This is accomplished through the construction of intrinsic color-curve templates allowing for the inference of optical and NIR color excesses, the host reddening, A host V , and (in some instances) the reddening-law parameter R host V . Armed with accurate estimates of host reddening, the CSP-I photometry sample is studied in detail in an additional companion paper by Taddia et al (2018). This includes the analysis of the light-curve properties and luminosities, the construction of light-curve templates, and UVOIR bolometric light curves.…”

“…In Stritzinger et al (2018), our SE SN photometry is used to devise robust methods to estimate host-galaxy extinction. Taddia et al (2018) use the photometry to construct UVOIR bolometric light curves which are modeled to estimate key explosion parameters. Finally, Holmbo et al (in prep.…”

Light Curves of Hydrogen-poor Superluminous Supernovae from the Palomar Transient Factory

“…These SNe are studied in more detail in Arcavi et al (2010), Corsi et al (2016), Prentice et al (2016), and Taddia et al (2018b), and will be presented in full in forthcoming publications (C. Barbarino et al 2018, in preparation;C. Fremling et al 2018, in preparation;E.…”