A meta-analysis of core-collapse supernova56Ni masses

Abstract

Context.A fundamental property determining the transient behaviour of core-collapse supernovae (CC SNe) is the amount of radioactive56Ni synthesised in the explosion. Using established methods, this is a relatively easy parameter to extract from observations.Aims.I provide a meta-analysis of all published56Ni masses for CC SNe.Methods.Collating a total of 258 literature56Ni masses, I compared distributions of the main CC SN types: SNe II, SNe IIb, SNe Ib, SNe Ic, and SNe IcBL.Results.Using these published values, I calculated a median56Ni mass of 0.032M⊙for SNe II (N = 115), 0.102M⊙for SNe IIb (N = 27), 0.163M⊙for SNe Ib (N = 33), 0.155M⊙for SNe Ic (N = 48), and 0.369M⊙for SNe IcBL (N = 32). On average, stripped-enevelope SNe (SE-SNe: IIb, Ib, Ic, and Ic-BL) have much higher values than SNe II. These observed distributions are compared to those predicted from neutrino-driven explosion models. While the SN II distribution follows model predictions, the SE-SNe have a significant fraction of events with56Ni masses much higher than predicted.Conclusions.If the majority of published56Ni masses are to be believed, these results imply significant differences in the progenitor structures and/or explosion properties between SNe II and SE-SNe. However, such distinct progenitor and explosion properties are not currently favoured in the literature. Alternatively, the popular methods used to estimate56Ni masses for SE-SNe may not be accurate. Possible issues with these methods are discussed, as are the implications of true56Ni mass differences on progenitor properties of different CC SNe.