A new method for estimating the bolometric properties of Ibc supernovae

The bolometric properties (nickel mass, ejecta mass and kinetic energies) of 61 Ibc supernovae (SNe), including 20 gamma-ray burst and X-ray flash (GRB/XRF), 19 Ib, 13 Ic and nine Ic-BL (broad-lined) SNe are presented. All of the available BVRI photometry in the literature have been collected and used in a new method that utilizes a template supernova (SN 1998bw) and an analytical model to accurately estimate the bolometric properties of each SN. A statistical analysis of the bolometric properties is then performed, where it is found that GRB/XRF SNe are the most energetic, and eject more mass (including nickel content) than Ib, Ic and Ic-BL SNe. The results are then compared to the existing progenitor models of Ibc SNe, where it is concluded that it is highly likely that at least two progenitor channels exist for producing a Ibc SN: most Ibc SNe arise via binary interactions, where the mass of the stellar progenitor is less than what is attributed to a Wolf-Rayet star. Conversely, the progenitors of Ic-BL and GRB/XRF are more massive than those of Ib and Ic SNe, and a key difference between GRB/XRF SNe and Ic-BL SNe is progenitor metallicity, where it is observed that the latter arise from more metal-rich progenitors. As mass loss in massive stars is influenced by metal content, the progenitors of Ic-BL SNe lose more mass, and therefore more angular momentum, before exploding. It is expected that the explosion mechanism in Ic-BL and GRB/XRF SNe is 'engine-driven' (i.e. an accreting black hole, or a millisecond magnetar), but the increased mass loss of Ic-BL SNe means the central engine is less powerful than in GRB/XRF SNe. Finally, it is found that the SNe that accompany GRBs and XRFs are statistically indistinguishable, and some mechanism other than metallicity is needed to explain the differences in the high-energy components in these events.