The death of massive stars - II. Observational constraints on the progenitors of type Ibc supernovae

TL;DR

This paper investigates the progenitors of type Ibc supernovae through extensive pre-explosion imaging, finding no direct detections and suggesting binary evolution as a key pathway for these supernovae.

Contribution

It provides observational constraints on type Ibc supernova progenitors and proposes binary evolution models as a plausible explanation for their characteristics.

Findings

No progenitors detected in 12 supernovae with deep imaging.

Progenitors are unlikely to be solely massive Wolf-Rayet stars.

Binary evolution models explain the observed properties of Ibc supernova progenitors.

Abstract

The progenitors of many type II core-collapse supernovae have now been identified directly on pre-discovery imaging. Here we present an extensive search for the progenitors of type Ibc supernovae in all available pre-discovery imaging since 1998. There are 12 type Ibc supernovae with no detections of progenitors in either deep ground-based or Hubble Space Telescope archival imaging. The deepest absolute BVR magnitude limits are between -4 and -5. We compare these limits with the observed Wolf-Rayet population in the Large Magellanic Cloud and estimate a 16 per cent probability we have failed to detect such a progenitor by chance. Alternatively the progenitors evolve significantly before core-collapse or we have underestimated the extinction towards the progenitors. Reviewing the relative rates and ejecta mass estimates from lightcurve modelling of Ibc SNe, we find both incompatible with Wolf-Rayet stars with initial masses >25Msun being the only progenitors. We present binary evolution models that fit these observational constraints. Stars in binaries with initial masses <20Msun lose their hydrogen envelopes in binary interactions to become low mass helium stars. They retain a low mass hydrogen envelope until approximately 10,000 years before core-collapse; hence it is not surprising that galactic analogues have been difficult to identify.